485BPOS

SEC File Nos. 002-10607

811-00572

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

Registration Statement

Under

the Securities Act of 1933

Post-Effective Amendment No. 128

and

Registration Statement

Under

the Investment Company Act of 1940

Amendment No. 48

AMERICAN MUTUAL FUND

(Exact Name of Registrant as Specified in Charter)

333 South Hope Street

Los Angeles, California 90071-1447

(Address of Principal Executive Offices)

Registrant's telephone number, including area code:

(213) 486-9200

Vincent P. Corti, Secretary

American Mutual Fund

333 South Hope Street

Los Angeles, California 90071-1447

(Name and Address of Agent for Service)

Copies to:

Eric A.S. Richards

O'Melveny & Myers LLP

400 South Hope Street

Los Angeles, California 90071-2899

(Counsel for the Registrant)

Approximate date of proposed public offering:

It is proposed that this filing become effective immediately pursuant to paragraph (b) of rule 485.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act of 1933 and has duly caused this registration statement to be signed on its behalf by the undersigned, duly authorized, in the City of Los Angeles, and State of California, on the 22^nd day of January, 2013.

AMERICAN MUTUAL FUND

By /s/ Joyce E. Gordon

(Joyce E. Gordon, Vice Chairman of the Board)

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below on January 22, 2013, by the following persons in the capacities indicated.

	Signature	Title
(1)	Principal Executive Officer:
	/s/ Paul F. Roye	President
	(Paul F. Roye)
(2)	Principal Financial Officer and Principal Accounting Officer:
	/s/ Ari M. Vinocor	Treasurer
	(Ari M. Vinocor)
(3)	Trustees:
	Louise H. Bryson*	Trustee
	Mary Anne Dolan*	Chairman of the Board (Independent and Non-Executive)
	James G. Ellis*	Trustee
	Leonard R. Fuller*	Trustee
	/s/ Joyce E. Gordon	Vice Chairman of the Board
	(Joyce E. Gordon)
	William D. Jones*	Trustee
	L. Daniel Jorndt*	Trustee
	William H. Kling*	Trustee
	John C. Mazziotta*	Trustee
	Bailey Morris-Eck*	Trustee
	Steven B. Sample*	Trustee
	*By /s/ Vincent P. Corti
	(Vincent P. Corti, pursuant to a power of attorney filed herewith)

Counsel represents that this amendment does not contain disclosures that would make the amendment ineligible for effectiveness under the provisions of rule 485(b).

/s/ Erik A. Vayntrub

(Erik A. Vayntrub)

POWER OF ATTORNEY

I, Louise H.Bryson, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Fundamental Investors (File No. 002-10760, File No. 811-00032)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

- The Growth Fund of America, Inc. (File No. 002-14728, File No. 811-00862)

- The Growth Fund of America

- The Investment Company of America (File No. 002-10811, File No. 811-00116)

- SMALLCAP World Fund, Inc. (File No. 033-32785, File No. 811-05888)

-     SMALLCAP World Fund

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Jeffrey P. Regal Ari M. Vinocor

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at San Marino, CA, this 1^st day of August, 2012.

(City, State)

/s/ Louise H. Bryson

Louise H. Bryson, Board member

POWER OF ATTORNEY

I, Mary AnneDolan, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Fundamental Investors (File No. 002-10760, File No. 811-00032)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

- Capital Income Builder (File No. 033-12967, File No. 811-05085)

- Capital World Growth and Income Fund, Inc. (File No. 033-54444, File No. 811-07338)

- Capital World Growth and Income Fund

- The Growth Fund of America, Inc. (File No. 002-14728, File No. 811-00862)

- The Growth Fund of America

- The Investment Company of America (File No. 002-10811, File No. 811-00116)

- The New Economy Fund (File No. 002-83848, File No. 811-03735)

- The New Economy Fund

- SMALLCAP World Fund, Inc. (File No. 033-32785, File No. 811-05888)

-     SMALLCAP World Fund

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Jeffrey P. Regal Ari M. Vinocor Neal F. Wellons

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Los Angeles, CA, this 3^rd day of August, 2012.

(City, State)

/s/ Mary Anne Dolan

Mary Anne Dolan, Board member

POWER OF ATTORNEY

I, James G.Ellis, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

-    AMCAP Fund (File No. 002-26516, File No. 811-01435)

-    American Funds College Target Date Series (File No. 333-180729, File No. 811-22692)

-    American Funds Corporate Bond Fund (File No. 333-183929, File No. 811-22744)

-    American Funds Global High-Income Opportunities Fund (File No. 333-183930, File No. 811-

-    American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

-    The American Funds Income Series – U.S. Government Securities Fund (File No. 002-98199, File No. 811-04318)

-    American Funds Inflation Linked Bond Fund (File No. 333-183931, File No. 811-22746)

-    American Funds Insurance Series (File No. 002-86838, File No. 811-03857)

-    American Funds Money Market Fund (File No. 333-157162, File No. 811-22277)

-    American Funds Mortgage Fund (File No. 333-168595, File No. 811-22449)

-    American Funds Portfolio Series (File No. 333-178936, File No. 811-22656)

-    American Funds Short-Term Tax-Exempt Bond Fund (File No. 033-26431, File No. 811-05750)

-    American Funds Target Date Retirement Series (File No. 333-138648, File No. 811-21981)

-    American Funds Tax-Exempt Fund of New York (File No. 333-168594, File No. 811-22448)

-    The American Funds Tax-Exempt Series II – The Tax-Exempt Fund of California (File No. 033-06180, File No. 811-04694)

-    American High-Income Municipal Bond Fund (File No. 033-80630, File No. 811-08576)

-    American High-Income Trust (File No. 033-17917, File No. 811-05364)

-    American Mutual Fund (File No. 002-10607, File No. 811-00572)

-    The Bond Fund of America (File No. 002-50700, File No. 811-02444)

-    Capital World Bond Fund (File No. 033-12447, File No. 811-05104)

-     Intermediate Bond Fund of America (File No. 033-19514, File No. 811-05446)

-    The Investment Company of America (File No. 002-10811, File No. 811-00116)

-     Limited Term Tax-Exempt Bond Fund of America (File No. 033-66214, File No. 811-07888)

-     Short-Term Bond Fund of America (File No. 333-135770, File No. 811-21928)

- The Tax-Exempt Bond Fund of America (File No. 002-49291, File No. 811-02421)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Brian C. Janssen Dori Laskin Gregory F. Niland Ari M. Vinocor

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Los Angeles, CA, this 5^th day of December, 2012.

(City, State)

/s/ James G. Ellis

James G. Ellis, Board member

POWER OF ATTORNEY

I, Leonard R.Fuller, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

-  AMCAP Fund (File No. 002-26516, File No. 811-01435)

-  American Funds College Target Date Series (File No. 333-180729, File No. 811-22692)

-  American Funds Corporate Bond Fund (File No. 333-183929, File No. 811-22744)

-  American Funds Global High-Income Opportunities Fund (File No. 333-183930, File No. 811-22745)

-  American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

-  The American Funds Income Series – U.S. Government Securities Fund (File No. 002-98199, File No. 811-04318)

-  American Funds Inflation Linked Bond Fund (File No. 333-183931, File No. 811-22746)

-  American Funds Insurance Series (File No. 002-86838, File No. 811-03857)

-  American Funds Money Market Fund (File No. 333-157162, File No. 811-22277)

-  American Funds Mortgage Fund (File No. 333-168595, File No. 811-22449)

-  American Funds Portfolio Series (File No. 333-178936, File No. 811-22656)

-  American Funds Short-Term Tax-Exempt Bond Fund (File No. 033-26431, File No. 811-05750)

-  American Funds Target Date Retirement Series (File No. 333-138648, File No. 811-21981)

-  American Funds Tax-Exempt Fund of New York (File No. 333-168594, File No. 811-22448)

-  The American Funds Tax-Exempt Series II – The Tax-Exempt Fund of California (File No. 033-06180, File No. 811-04694)

-  American High-Income Municipal Bond Fund (File No. 033-80630, File No. 811-08576)

-  American High-Income Trust (File No. 033-17917, File No. 811-05364)

-  American Mutual Fund (File No. 002-10607, File No. 811-00572)

-  The Bond Fund of America (File No. 002-50700, File No. 811-02444)

-  Capital World Bond Fund (File No. 033-12447, File No. 811-05104)

-  Intermediate Bond Fund of America (File No. 033-19514, File No. 811-05446)

-  The Investment Company of America (File No. 002-10811, File No. 811-00116)

-  Limited Term Tax-Exempt Bond Fund of America (File No. 033-66214, File No. 811-07888)

-  Short-Term Bond Fund of America (File No. 333-135770, File No. 811-21928)

- The Tax-Exempt Bond Fund of America (File No. 002-49291, File No. 811-02421)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Brian C. Janssen Dori Laskin Gregory F. Niland Ari M. Vinocor

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Los Angeles, CA, this 5^th day of December, 2012.

(City, State)

/s/ Leonard R. Fuller

Leonard R. Fuller, Board member

POWER OF ATTORNEY

I, William D.Jones, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Balanced Fund (File No. 002-10758, File No. 811-00066)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

- The Income Fund of America (File No. 002-33371, File No. 811-01880)

- International Growth and Income Fund (File No. 333-152323, File No. 811-22215)

-     The Investment Company of America (File No. 002-10811, File No. 811-00116)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman M. Susan Gupton Jeffrey P. Regal Ari M. Vinocor  

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at San Diego, CA, this 3^rd day of August, 2012.

(City, State)

/s/ William D. Jones

William D. Jones, Board member

POWER OF ATTORNEY

I, L. DanielJorndt, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

-     The Investment Company of America (File No. 002-10811, File No. 811-00116)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Ari M. Vinocor  

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Deerfield, IL, this 6^th day of August, 2012.

(City, State)

/s/ L. Daniel Jorndt

L. Daniel Jorndt, Board member

POWER OF ATTORNEY

I, William H.Kling, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Fundamental Investors (File No. 002-10760, File No. 811-00032)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

- EuroPacific Growth Fund (File No. 002-83847, File No. 811-03734)

- EuroPacific Growth Fund

- The Growth Fund of America, Inc. (File No. 002-14728, File No. 811-00862)

- The Growth Fund of America

- The Investment Company of America (File No. 002-10811, File No. 811-00116)

- New Perspective Fund, Inc. (File No. 002-47749, File No. 811-02333)

- New Perspective Fund

- New World Fund, Inc. (File No. 333-67455, File No. 811-09105)

- American Funds New World Fund

- SMALLCAP World Fund, Inc. (File No. 033-32785, File No. 811-05888)

-     SMALLCAP World Fund

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Brian C. Janssen Jeffrey P. Regal Ari M. Vinocor

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

 EXECUTED at Minneapolis, MN, this 6^th day of August, 2012.

(City, State)

/s/ William H. Kling

William H. Kling, Board member

POWER OF ATTORNEY

I, John C.Mazziotta, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

-     The Investment Company of America (File No. 002-10811, File No. 811-00116)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Ari M. Vinocor  

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Los Angeles, CA, this 1^st day of August, 2012.

(City, State)

/s/ John C. Mazziotta

John C. Mazziotta, Board member

POWER OF ATTORNEY

I, BaileyMorris-Eck, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

-     The Investment Company of America (File No. 002-10811, File No. 811-00116)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Ari M. Vinocor  

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Butler, MD, this 8^th day of August, 2012.

(City, State)

/s/ Bailey Morris-Eck

Bailey Morris-Eck, Board member

POWER OF ATTORNEY

I, Steven B.Sample, the undersigned Board member of the following registered investment companies (collectively, the “Funds”):

- AMCAP Fund (File No. 002-26516, File No. 811-01435)

- American Funds Global Balanced Fund (File No. 333-170605, File No. 811-22496)

- American Mutual Fund (File No. 002-10607, File No. 811-00572)

-         The Investment Company of America (File No. 002-10811, File No. 811-00116)

hereby revoke all previous powers of attorney I have signed and otherwise act in my name and behalf in matters involving the Funds and do hereby constitute and appoint

Vincent P. Corti Steven I. Koszalka Patrick F. Quan Courtney R. Taylor Julie E. Lawton Tanya Schneider Raymond F. Sullivan, Jr. Brian D. Bullard Karl C. Grauman Ari M. Vinocor  

each of them singularly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, any and all subsequent Amendments, or Post-Effective Amendments to said Registration Statement on Form N-1A or any successor thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940 as amended, and all related requirements of the U. S. Securities and Exchange Commission. I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.

EXECUTED at Los Angeles, CA, this 7^th day of August, 2012.

(City, State)

/s/ Steven B. Sample

Steven B. Sample, Board member

Exhibit Index

Exhibit No.	Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 01, 2013
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	American Mutual Fund®
Objective [Heading]	rr_ObjectiveHeading	Investment objectives
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund strives for the balanced accomplishment of three objectives: current income, growth of capital and conservation of principal.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses of the fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in American Funds. More information about these and other discounts is available from your financial professional and in the "Sales charge reductions and waivers" section on page 26 of the prospectus and on page 57 of the fund's statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund's investment results. During the most recent fiscal year, the fund's portfolio turnover rate was 22% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	22.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in American Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same.
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	For the share classes listed below, you would pay the following if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal investment strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The fund seeks to invest primarily in common stocks of companies that are likely to participate in the growth of the American economy and whose dividends appear to be sustainable. The fund invests primarily in securities of issuers domiciled in the United States and Canada. The fund's equity investments are limited to securities of companies that are included on its eligible list. In light of the fund's investment objectives and policies, securities are added to, or deleted from, the eligible list by the fund's board of trustees after reviewing and acting upon the recommendations of the fund's investment adviser. The investment adviser bases its recommendations on a number of factors, such as the fund's investment objectives and policies, whether a company is considered a leader in its industry and a company's dividend payment prospects. Although the fund focuses on investments in medium to larger capitalization companies, the fund's investments are not limited to a particular capitalization size. The fund may also invest in bonds and other debt securities, including those issued by the U.S. government and by federal agencies and instrumentalities. Debt securities purchased by the fund are rated investment grade or better or determined by the fund's investment adviser to be of equivalent quality. The investment adviser uses a system of multiple portfolio counselors in managing the fund's assets. Under this approach, the portfolio of the fund is divided into segments managed by individual counselors who decide how their respective segments will be invested. The fund relies on the professional judgment of its investment adviser to make decisions about the fund's portfolio investments. The basic investment philosophy of the investment adviser is to seek to invest in attractively valued companies that, in its opinion, represent good, long-term investment opportunities. The investment adviser believes that an important way to accomplish this is through fundamental analysis, which may include meeting with company executives and employees, suppliers, customers and competitors. Securities may be sold when the investment adviser believes that they no longer represent relatively attractive investment opportunities.
Risk [Heading]	rr_RiskHeading	Principal risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	This section describes the principal risks associated with the fund's principal investment strategies. You may lose money by investing in the fund. The likelihood of loss may be greater if you invest for a shorter period of time. Investors in the fund should have a long-term perspective and be able to tolerate potentially sharp declines in value. Market conditions - The prices of, and the income generated by, the common stocks and other securities held by the fund may decline due to market conditions and other factors, including those directly involving the issuers of securities held by the fund. Investing in growth-oriented stocks - Growth-oriented stocks may involve larger price swings and greater potential for loss than other types of investments. Investing in income-oriented stocks - Income provided by the fund may be reduced by changes in the dividend policies of, and the capital resources available at, the companies in which the fund invests. Investing in bonds - Rising interest rates will generally cause the prices of bonds and other debt securities to fall. Longer maturity debt securities may be subject to greater price fluctuations than shorter maturity debt securities. In addition, falling interest rates may cause an issuer to redeem, call or refinance a security before its stated maturity, which may result in the fund having to reinvest the proceeds in lower yielding securities. Bonds and other debt securities are subject to credit risk, which is the possibility that the credit strength of an issuer will weaken and/or an issuer of a debt security will fail to make timely payments of principal or interest and the security will go into default. Lower quality debt securities generally have higher rates of interest and may be subject to greater price fluctuations than higher quality debt securities. Credit risk is gauged, in part, by the credit ratings of the securities in which the fund invests. However, ratings are only the opinions of the rating agencies issuing them and are not guarantees as to credit quality or an evaluation of market risk. Management - The investment adviser to the fund actively manages the fund's investments. Consequently, the fund is subject to the risk that the methods and analyses employed by the investment adviser in this process may not produce the desired results. This could cause the fund to lose value or its investment results to lag relevant benchmarks or other funds with similar objectives. Your investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, entity or person. You should consider how this fund fits into your overall investment program.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	Your investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, entity or person.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Investment results
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart shows how the fund's investment results have varied from year to year, and the following table shows how the fund's average annual total returns for various periods compare with different broad measures of market results. This information provides some indication of the risks of investing in the fund. Lipper Large-Cap Value Funds Index includes the fund and other funds that disclose investment objectives and/or strategies reasonably comparable to the fund's objectives and/or strategies. Lipper Growth and Income Funds Index also includes the fund and other funds that disclose investment objectives and/or strategies reasonably comparable to the fund's objectives and/or strategies. Past investment results (before and after taxes) are not predictive of future investment results. Updated information on the fund's investment results can be obtained by visiting americanfunds.com.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart shows how the fund's investment results have varied from year to year, and the following table shows how the fund's average annual total returns for various periods compare with different broad measures of market results.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	Lipper Large-Cap Value Funds Index includes the fund and other funds that disclose investment objectives and/or strategies reasonably comparable to the fund's objectives and/or strategies. Lipper Growth and Income Funds Index also includes the fund and other funds that disclose investment objectives and/or strategies reasonably comparable to the fund's objectives and/or strategies.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	americanfunds.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Past investment results (before and after taxes) are not predictive of future investment results.
Bar Chart [Heading]	rr_BarChartHeading	Calendar year total returns for Class A shares (Results do not include a sales charge; if a sales charge were included, results would be lower.)
Bar Chart Narrative [Text Block]	rr_BarChartNarrativeTextBlock	The following bar chart shows how the fund's investment results have varied from year to year, and the following table shows how the fund's average annual total returns for various periods compare with different broad measures of market results.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	(Results do not include a sales charge; if a sales charge were included, results would be lower.)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest/Lowest quarterly results during this period were: Highest  13.40% (quarter ended June 30, 2009) Lowest  -17.52% (quarter ended December 31, 2008) The fund's total return for the nine months ended September 30, 2012, was 11.50%.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the highest individual federal income tax rates in effect during each year of the periods shown and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Your actual after-tax returns depend on your individual tax situation and likely will differ from the results shown above. In addition, after-tax returns are not relevant if you hold your fund shares through a tax-favored arrangement, such as a 401(k) plan, individual retirement account (IRA) or 529 college savings plan.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown only for Class A shares; after-tax returns for other share classes will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are shown only for Class A shares; after-tax returns for other share classes will vary. After-tax returns are calculated using the highest individual federal income tax rates in effect during each year of the periods shown and do not reflect the impact of state and local taxes. Your actual after-tax returns depend on your individual tax situation and likely will differ from the results shown above. In addition, after-tax returns are not relevant if you hold your fund shares through a tax-favored arrangement, such as a 401(k) plan, individual retirement account (IRA) or 529 college savings plan.
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	Class A annualized 30-day yield at October 31, 2012: 2.08% (For current yield information, please call American FundsLine® at 800/325-3590.)
Caption	rr_AverageAnnualReturnCaption	Average annual total returns For the periods ended December 31, 2011 (with maximum sales charge):
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | S&P 500
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500 (reflects no deductions for sales charges, account fees, expenses or U.S. federal income taxes)
1 Year	rr_AverageAnnualReturnYear01	2.09%
5 Years	rr_AverageAnnualReturnYear05	(0.25%)
10 Years	rr_AverageAnnualReturnYear10	2.92%
Since Inception	rr_AverageAnnualReturnSinceInception	10.93%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 21, 1950
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Lipper Large-Cap Value Funds Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Lipper Large-Cap Value Funds Index (reflects no deductions for sales charges, account fees or U.S. federal income taxes)
1 Year	rr_AverageAnnualReturnYear01	(2.17%)
5 Years	rr_AverageAnnualReturnYear05	(2.26%)
10 Years	rr_AverageAnnualReturnYear10	2.59%
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Lipper Growth and Income Funds Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Lipper Growth and Income Funds Index (reflects no deductions for sales charges, account fees or U.S. federal income taxes)
1 Year	rr_AverageAnnualReturnYear01	(1.82%)
5 Years	rr_AverageAnnualReturnYear05	(1.17%)
10 Years	rr_AverageAnnualReturnYear10	3.12%
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[1]
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.23%
Other expenses	rr_OtherExpensesOverAssets	0.15%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.63%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	636
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	765
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	906
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,316
Annual Return 2002	rr_AnnualReturn2002	(12.18%)
Annual Return 2003	rr_AnnualReturn2003	23.31%
Annual Return 2004	rr_AnnualReturn2004	10.74%
Annual Return 2005	rr_AnnualReturn2005	4.94%
Annual Return 2006	rr_AnnualReturn2006	16.24%
Annual Return 2007	rr_AnnualReturn2007	3.33%
Annual Return 2008	rr_AnnualReturn2008	(30.04%)
Annual Return 2009	rr_AnnualReturn2009	25.43%
Annual Return 2010	rr_AnnualReturn2010	12.23%
Annual Return 2011	rr_AnnualReturn2011	4.77%
Year to Date Return, Label	rr_YearToDateReturnLabel	The fund's total return for the nine months ended
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	11.50%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	13.40%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(17.52%)
Label	rr_AverageAnnualReturnLabel	Share class A - Before taxes
1 Year	rr_AverageAnnualReturnYear01	(1.24%)
5 Years	rr_AverageAnnualReturnYear05	0.10%
10 Years	rr_AverageAnnualReturnYear10	3.93%
Since Inception	rr_AverageAnnualReturnSinceInception	11.42%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 21, 1950
Thirty Day Yield Caption	rr_ThirtyDayYieldCaption	Class A annualized 30-day yield at October 31, 2012:
Thirty Day Yield Phone	rr_ThirtyDayYieldPhone	800/325-3590
Thirty Day Yield	rr_ThirtyDayYield	2.08%
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class A | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Share class A - After taxes on distributions
1 Year	rr_AverageAnnualReturnYear01	(1.61%)
5 Years	rr_AverageAnnualReturnYear05	(0.46%)
10 Years	rr_AverageAnnualReturnYear10	3.28%
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class A | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Share class A - After taxes on distributions and sale of fund shares
1 Year	rr_AverageAnnualReturnYear01	(0.32%)
5 Years	rr_AverageAnnualReturnYear05	0.02%
10 Years	rr_AverageAnnualReturnYear10	3.25%
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class B
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.14%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.39%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	642
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	840
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	961
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,461
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	142
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	440
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	761
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,461
Label	rr_AverageAnnualReturnLabel	Share class B (before taxes)
1 Year	rr_AverageAnnualReturnYear01	(1.03%)
5 Years	rr_AverageAnnualReturnYear05	0.15%
10 Years	rr_AverageAnnualReturnYear10	3.89%
Since Inception	rr_AverageAnnualReturnSinceInception	5.35%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 15, 2000
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.18%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.43%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	246
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	452
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	782
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,713
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	146
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	452
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	782
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,713
Label	rr_AverageAnnualReturnLabel	Share class C (before taxes)
1 Year	rr_AverageAnnualReturnYear01	2.94%
5 Years	rr_AverageAnnualReturnYear05	0.46%
10 Years	rr_AverageAnnualReturnYear10	3.67%
Since Inception	rr_AverageAnnualReturnSinceInception	4.05%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 15, 2001
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.17%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.67%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	68
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	214
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	373
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	835
Label	rr_AverageAnnualReturnLabel	Share class F-1 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.75%
5 Years	rr_AverageAnnualReturnYear05	1.26%
10 Years	rr_AverageAnnualReturnYear10	4.48%
Since Inception	rr_AverageAnnualReturnSinceInception	4.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 15, 2001
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class F-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.18%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.43%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	44
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	138
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	241
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	542
Label	rr_AverageAnnualReturnLabel	Share class F-2 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.99%
Since Inception	rr_AverageAnnualReturnSinceInception	3.73%
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 05, 2008
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-A
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.75%
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[1]
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Maximum annual account fee (529 share classes only)	rr_MaximumAccountFee	10
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.21%
Other expenses	rr_OtherExpensesOverAssets	0.26%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.72%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	664
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	831
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,011
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,523
Label	rr_AverageAnnualReturnLabel	Share class 529-A (before taxes)
1 Year	rr_AverageAnnualReturnYear01	(1.32%)
5 Years	rr_AverageAnnualReturnYear05	0.01%
Since Inception	rr_AverageAnnualReturnSinceInception	4.22%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 19, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-B
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Maximum annual account fee (529 share classes only)	rr_MaximumAccountFee	10
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.99%
Other expenses	rr_OtherExpensesOverAssets	0.28%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.52%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	674
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	919
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,086
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,698
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	174
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	519
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	886
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,698
Label	rr_AverageAnnualReturnLabel	Share class 529-B (before taxes)
1 Year	rr_AverageAnnualReturnYear01	(1.12%)
5 Years	rr_AverageAnnualReturnYear05	0.05%
Since Inception	rr_AverageAnnualReturnSinceInception	4.13%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 19, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Maximum annual account fee (529 share classes only)	rr_MaximumAccountFee	10
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.99%
Other expenses	rr_OtherExpensesOverAssets	0.27%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.51%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	273
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	516
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	881
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,901
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	173
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	516
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	881
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,901
Label	rr_AverageAnnualReturnLabel	Share class 529-C (before taxes)
1 Year	rr_AverageAnnualReturnYear01	2.88%
5 Years	rr_AverageAnnualReturnYear05	0.40%
Since Inception	rr_AverageAnnualReturnSinceInception	3.88%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 20, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-E
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Maximum annual account fee (529 share classes only)	rr_MaximumAccountFee	10
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.98%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	120
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	351
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	600
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,305
Label	rr_AverageAnnualReturnLabel	Share class 529-E (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.42%
5 Years	rr_AverageAnnualReturnYear05	0.91%
Since Inception	rr_AverageAnnualReturnSinceInception	3.83%
Inception Date	rr_AverageAnnualReturnInceptionDate	Mar. 07, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Maximum annual account fee (529 share classes only)	rr_MaximumAccountFee	10
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.26%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.51%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	72
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	203
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	344
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	747
Label	rr_AverageAnnualReturnLabel	Share class 529-F-1 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.95%
5 Years	rr_AverageAnnualReturnYear05	1.42%
Since Inception	rr_AverageAnnualReturnSinceInception	6.56%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 17, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.18%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.43%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	146
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	452
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	782
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,713
Label	rr_AverageAnnualReturnLabel	Share class R-1 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	3.92%
5 Years	rr_AverageAnnualReturnYear05	0.45%
Since Inception	rr_AverageAnnualReturnSinceInception	4.04%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 11, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.74%
Other expenses	rr_OtherExpensesOverAssets	0.44%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.43%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	146
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	452
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	782
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,713
Label	rr_AverageAnnualReturnLabel	Share class R-2 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	3.95%
5 Years	rr_AverageAnnualReturnYear05	0.41%
Since Inception	rr_AverageAnnualReturnSinceInception	3.64%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 31, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-3
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other expenses	rr_OtherExpensesOverAssets	0.22%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.97%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	99
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	309
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	536
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,190
Label	rr_AverageAnnualReturnLabel	Share class R-3 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.44%
5 Years	rr_AverageAnnualReturnYear05	0.92%
Since Inception	rr_AverageAnnualReturnSinceInception	4.44%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 06, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-4
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.16%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.66%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	67
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	211
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	368
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	822
Label	rr_AverageAnnualReturnLabel	Share class R-4 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	4.73%
5 Years	rr_AverageAnnualReturnYear05	1.23%
Since Inception	rr_AverageAnnualReturnSinceInception	5.09%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jun. 27, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-5
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.12%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.37%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	38
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	119
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	208
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	468
Label	rr_AverageAnnualReturnLabel	Share class R-5 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	5.07%
5 Years	rr_AverageAnnualReturnYear05	1.53%
Since Inception	rr_AverageAnnualReturnSinceInception	4.63%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 15, 2002
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-6
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Maximum sales charge (load) imposed on reinvested dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption or exchange fees	rr_RedemptionFee	none
Management fees	rr_ManagementFeesOverAssets	0.25%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.07%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.32%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	33
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	103
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	180
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	406
Label	rr_AverageAnnualReturnLabel	Share class R-6 (before taxes)
1 Year	rr_AverageAnnualReturnYear01	5.08%
Since Inception	rr_AverageAnnualReturnSinceInception	16.41%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 01, 2009

[1] A contingent deferred sales charge of 1.00% applies on certain redemptions within one year following purchases of $1 million or more made without an initial sales charge.

XML

AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC

American Mutual Fund®

Investment objectives

The fund strives for the balanced accomplishment of three objectives: current
income, growth of capital and conservation of principal.

Fees and expenses of the fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the fund. You may qualify for sales charge discounts if you and your
family invest, or agree to invest in the future, at least $25,000 in American
Funds. More information about these and other discounts is available from your
financial professional and in the "Sales charge reductions and waivers" section
on page 26 of the prospectus and on page 57 of the fund's statement of
additional information.

Shareholder fees (fees paid directly from your investment)

Shareholder Fees AMERICAN MUTUAL FUND INC (USD $)	Class A		Class B	Class C	Class F-1	Class F-2	Class 529-A		Class 529-B	Class 529-C	Class 529-E	Class 529-F-1	Class R-1	Class R-2	Class R-3	Class R-4	Class R-5	Class R-6
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	none	none	5.75%		none	none	none	none	none	none	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of the amount redeemed)	1.00%	[1]	5.00%	1.00%	none	none	1.00%	[1]	5.00%	1.00%	none	none	none	none	none	none	none	none
Maximum sales charge (load) imposed on reinvested dividends	none		none	none	none	none	none		none	none	none	none	none	none	none	none	none	none
Redemption or exchange fees	none		none	none	none	none	none		none	none	none	none	none	none	none	none	none	none
Maximum annual account fee (529 share classes only)							10		10	10	10	10

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses AMERICAN MUTUAL FUND INC	Class A	Class B	Class C	Class F-1	Class F-2	Class 529-A	Class 529-B	Class 529-C	Class 529-E	Class 529-F-1	Class R-1	Class R-2	Class R-3	Class R-4	Class R-5	Class R-6
Management fees	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%	0.25%
Distribution and/or service (12b-1) fees	0.23%	1.00%	1.00%	0.25%	none	0.21%	0.99%	0.99%	0.50%	none	1.00%	0.74%	0.50%	0.25%	none	none
Other expenses	0.15%	0.14%	0.18%	0.17%	0.18%	0.26%	0.28%	0.27%	0.23%	0.26%	0.18%	0.44%	0.22%	0.16%	0.12%	0.07%
Total annual fund operating expenses	0.63%	1.39%	1.43%	0.67%	0.43%	0.72%	1.52%	1.51%	0.98%	0.51%	1.43%	1.43%	0.97%	0.66%	0.37%	0.32%

Example

This example is intended to help you compare the cost of investing in
the fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods
indicated and then redeem all of your shares at the end of those periods. The
example also assumes that your investment has a 5% return each year and that the
fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example AMERICAN MUTUAL FUND INC (USD $)	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
Class A	636	765	906	1,316
Class B	642	840	961	1,461
Class C	246	452	782	1,713
Class F-1	68	214	373	835
Class F-2	44	138	241	542
Class 529-A	664	831	1,011	1,523
Class 529-B	674	919	1,086	1,698
Class 529-C	273	516	881	1,901
Class 529-E	120	351	600	1,305
Class 529-F-1	72	203	344	747
Class R-1	146	452	782	1,713
Class R-2	146	452	782	1,713
Class R-3	99	309	536	1,190
Class R-4	67	211	368	822
Class R-5	38	119	208	468
Class R-6	33	103	180	406

For the share classes listed below, you would pay the following if you did not redeem your shares:

Expense Example, No Redemption AMERICAN MUTUAL FUND INC (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years	Expense Example, No Redemption, 5 Years	Expense Example, No Redemption, 10 Years
Class B	142	440	761	1,461
Class C	146	452	782	1,713
Class 529-B	174	519	886	1,698
Class 529-C	173	516	881	1,901

Portfolio turnover

The fund pays transaction costs, such as commissions, when it buys and sells
securities (or "turns over" its portfolio). A higher portfolio turnover rate
may indicate higher transaction costs and may result in higher taxes when fund
shares are held in a taxable account. These costs, which are not reflected in
annual fund operating expenses or in the example, affect the fund's investment
results. During the most recent fiscal year, the fund's portfolio turnover rate
was 22% of the average value of its portfolio.

Principal investment strategies

The fund seeks to invest primarily in common stocks of companies that are likely
to participate in the growth of the American economy and whose dividends appear
to be sustainable. The fund invests primarily in securities of issuers domiciled
in the United States and Canada.

The fund's equity investments are limited to securities of companies that are
included on its eligible list. In light of the fund's investment objectives and
policies, securities are added to, or deleted from, the eligible list by the
fund's board of trustees after reviewing and acting upon the recommendations of
the fund's investment adviser. The investment adviser bases its recommendations
on a number of factors, such as the fund's investment objectives and policies,
whether a company is considered a leader in its industry and a company's
dividend payment prospects. Although the fund focuses on investments in medium
to larger capitalization companies, the fund's investments are not limited to a
particular capitalization size.

The fund may also invest in bonds and other debt securities, including those
issued by the U.S. government and by federal agencies and instrumentalities.
Debt securities purchased by the fund are rated investment grade or better or
determined by the fund's investment adviser to be of equivalent quality.

The investment adviser uses a system of multiple portfolio counselors in
managing the fund's assets. Under this approach, the portfolio of the fund is
divided into segments managed by individual counselors who decide how their
respective segments will be invested.

The fund relies on the professional judgment of its investment adviser to make
decisions about the fund's portfolio investments. The basic investment philosophy
of the investment adviser is to seek to invest in attractively valued companies
that, in its opinion, represent good, long-term investment opportunities. The
investment adviser believes that an important way to accomplish this is through
fundamental analysis, which may include meeting with company executives and
employees, suppliers, customers and competitors. Securities may be sold when
the investment adviser believes that they no longer represent relatively
attractive investment opportunities.

Principal risks

This section describes the principal risks associated with the fund's principal
investment strategies. You may lose money by investing in the fund. The
likelihood of loss may be greater if you invest for a shorter period of time.
Investors in the fund should have a long-term perspective and be able to
tolerate potentially sharp declines in value.

Market conditions - The prices of, and the income generated by, the common
stocks and other securities held by the fund may decline due to market
conditions and other factors, including those directly involving the issuers of
securities held by the fund.

Investing in growth-oriented stocks - Growth-oriented stocks may involve larger
price swings and greater potential for loss than other types of investments.

Investing in income-oriented stocks - Income provided by the fund may be reduced
by changes in the dividend policies of, and the capital resources available at,
the companies in which the fund invests.

Investing in bonds - Rising interest rates will generally cause the prices of
bonds and other debt securities to fall. Longer maturity debt securities may be
subject to greater price fluctuations than shorter maturity debt securities. In
addition, falling interest rates may cause an issuer to redeem, call or refinance
a security before its stated maturity, which may result in the fund having to
reinvest the proceeds in lower yielding securities.

Bonds and other debt securities are subject to credit risk, which is the
possibility that the credit strength of an issuer will weaken and/or an issuer
of a debt security will fail to make timely payments of principal or interest
and the security will go into default. Lower quality debt securities generally
have higher rates of interest and may be subject to greater price fluctuations
than higher quality debt securities. Credit risk is gauged, in part, by the
credit ratings of the securities in which the fund invests. However, ratings are
only the opinions of the rating agencies issuing them and are not guarantees as
to credit quality or an evaluation of market risk.

Management - The investment adviser to the fund actively manages the fund's
investments. Consequently, the fund is subject to the risk that the methods and
analyses employed by the investment adviser in this process may not produce the
desired results. This could cause the fund to lose value or its investment
results to lag relevant benchmarks or other funds with similar objectives.

Your investment in the fund is not a bank deposit and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other
governmental agency, entity or person. You should consider how this fund
fits into your overall investment program.

Investment results

The following bar chart shows how the fund's investment results have varied from
year to year, and the following table shows how the fund's average annual total
returns for various periods compare with different broad measures of market
results. This information provides some indication of the risks of investing in
the fund. Lipper Large-Cap Value Funds Index includes the fund and other funds
that disclose investment objectives and/or strategies reasonably comparable to
the fund's objectives and/or strategies. Lipper Growth and Income Funds Index
also includes the fund and other funds that disclose investment objectives
and/or strategies reasonably comparable to the fund's objectives and/or
strategies. Past investment results (before and after taxes) are not predictive
of future investment results. Updated information on the fund's investment
results can be obtained by visiting americanfunds.com.

The following bar chart shows how the fund's investment results have varied from
year to year, and the following table shows how the fund's average annual total
returns for various periods compare with different broad measures of market
results.

Calendar year total returns for Class A shares (Results do not include a sales charge; if a sales charge were included, results would be lower.)

Highest/Lowest quarterly results during this period were:

Highest  13.40% (quarter ended June 30, 2009)

Lowest  -17.52% (quarter ended December 31, 2008)

The fund's total return for the nine months ended September 30, 2012,
was 11.50%.

After-tax returns are shown only for Class A shares; after-tax returns for other
share classes will vary. After-tax returns are calculated using the highest
individual federal income tax rates in effect during each year of the periods
shown and do not reflect the impact of state and local taxes. Your actual
after-tax returns depend on your individual tax situation and likely will differ
from the results shown above. In addition, after-tax returns are not relevant if
you hold your fund shares through a tax-favored arrangement, such as a 401(k)
plan, individual retirement account (IRA) or 529 college savings plan.

Average annual total returns For the periods ended December 31, 2011 (with maximum sales charge):

Average Annual Total Returns AMERICAN MUTUAL FUND INC	Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Class A	Share class A - Before taxes	(1.24%)	0.10%	3.93%	11.42%	Feb. 21, 1950
Class B	Share class B (before taxes)	(1.03%)	0.15%	3.89%	5.35%	Mar. 15, 2000
Class C	Share class C (before taxes)	2.94%	0.46%	3.67%	4.05%	Mar. 15, 2001
Class F-1	Share class F-1 (before taxes)	4.75%	1.26%	4.48%	4.80%	Mar. 15, 2001
Class F-2	Share class F-2 (before taxes)	4.99%			3.73%	Aug. 05, 2008
Class 529-A	Share class 529-A (before taxes)	(1.32%)	0.01%		4.22%	Feb. 19, 2002
Class 529-B	Share class 529-B (before taxes)	(1.12%)	0.05%		4.13%	Feb. 19, 2002
Class 529-C	Share class 529-C (before taxes)	2.88%	0.40%		3.88%	Feb. 20, 2002
Class 529-E	Share class 529-E (before taxes)	4.42%	0.91%		3.83%	Mar. 07, 2002
Class 529-F-1	Share class 529-F-1 (before taxes)	4.95%	1.42%		6.56%	Sep. 17, 2002
Class R-1	Share class R-1 (before taxes)	3.92%	0.45%		4.04%	Jun. 11, 2002
Class R-2	Share class R-2 (before taxes)	3.95%	0.41%		3.64%	May 31, 2002
Class R-3	Share class R-3 (before taxes)	4.44%	0.92%		4.44%	Jun. 06, 2002
Class R-4	Share class R-4 (before taxes)	4.73%	1.23%		5.09%	Jun. 27, 2002
Class R-5	Share class R-5 (before taxes)	5.07%	1.53%		4.63%	May 15, 2002
Class R-6	Share class R-6 (before taxes)	5.08%			16.41%	May 01, 2009
After Taxes on Distributions Class A	Share class A - After taxes on distributions	(1.61%)	(0.46%)	3.28%
After Taxes on Distributions and Sales Class A	Share class A - After taxes on distributions and sale of fund shares	(0.32%)	0.02%	3.25%
S&P 500	S&P 500 (reflects no deductions for sales charges, account fees, expenses or U.S. federal income taxes)	2.09%	(0.25%)	2.92%	10.93%	Feb. 21, 1950
Lipper Large-Cap Value Funds Index	Lipper Large-Cap Value Funds Index (reflects no deductions for sales charges, account fees or U.S. federal income taxes)	(2.17%)	(2.26%)	2.59%
Lipper Growth and Income Funds Index	Lipper Growth and Income Funds Index (reflects no deductions for sales charges, account fees or U.S. federal income taxes)	(1.82%)	(1.17%)	3.12%

Class A annualized 30-day yield at October 31, 2012: 2.08%
(For current yield information, please call American
FundsLine® at 800/325-3590.)

[1] A contingent deferred sales charge of 1.00% applies on certain redemptions within one year following purchases of $1 million or more made without an initial sales charge.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Oct. 31, 2012
Registrant Name	dei_EntityRegistrantName	AMERICAN MUTUAL FUND
Central Index Key	dei_EntityCentralIndexKey	0000005506
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Dec. 28, 2012
Document Effective Date	dei_DocumentEffectiveDate	Jan. 01, 2013
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AMRMX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class B
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AMFBX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AMFCX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AMFFX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class F-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	AMRFX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CMLAX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-B
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CMLBX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CMLCX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-E
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CMLEX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class 529-F-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	CMLFX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-1
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFAX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-2
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFBX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-3
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFCX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-4
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFEX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-5
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFFX
AMERICAN MUTUAL FUND INC (Prospectus Summary) | AMERICAN MUTUAL FUND INC | Class R-6
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	RMFGX