dei_EntityRegistrantName

JANUS INVESTMENT FUND

rr_SupplementToProspectusTextBlock

Janus Investment Fund

Janus Henderson Short-Term Bond Fund


Class A Shares	Class S Shares	Class N Shares
Class C Shares	Class I Shares	Class T Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

The Board of Trustees of Janus Investment Fund approved a new management fee rate for Janus Henderson Short-Term Bond Fund (the “Fund”), effective December 14, 2018, that reduces the management fee rate paid by the Fund to Janus Capital Management LLC to 0.44%. A comparison of the Fund’s prior and new annual management fee rate schedule (expressed as an annual rate) is shown below.


PRIOR FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
First $300 Million Over $300 Million		0.64 0.54

NEW FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
All Asset Levels		0.44

In response to the above changes, the Fund’s Prospectuses are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Management Fees⁽¹⁾	0.44%	0.44%	0.44%	0.44%	0.44%	0.44%
Distribution/Services (12b-1) Fees	0.25%	1.00%	0.25%	None	None	None
Other Expenses	0.10%	0.13%	0.34%	0.13%	0.06%	0.29%
Total Annual Fund Operating Expenses⁽²⁾	0.79%	1.57%	1.03%	0.57%	0.50%	0.73%
Fee Waiver⁽²⁾	0.05%	0.05%	0.09%	0.05%	0.06%	0.04%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾	0.74%	1.52%	0.94%	0.52%	0.44%	0.69%

(1)	Annual Fund Operating Expenses were restated, effective December 14, 2018, to reflect a reduction to the Management Fee paid by the Fund to Janus Capital.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.44% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

2.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:

EXAMPLE:

The following Example is based on expenses without waivers. The 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 reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


If Shares are redeemed:	1 Year			3 Years			5 Years			10 Years
Class A Shares		$	329		$	496		$	678		$	1,203
Class C Shares		$	260		$	496		$	855		$	1,867
Class S Shares		$	105		$	328		$	569		$	1,259
Class I Shares		$	58		$	183		$	318		$	714
Class N Shares		$	51		$	160		$	280		$	628
Class T Shares		$	75		$	233		$	406		$	906

If Shares are not redeemed:	1 Year			3 Years			5 Years			10 Years
Class A Shares		$	329		$	496		$	678		$	1,203
Class C Shares		$	160		$	496		$	855		$	1,867
Class S Shares		$	105		$	328		$	569		$	1,259
Class I Shares		$	58		$	183		$	318		$	714
Class N Shares		$	51		$	160		$	280		$	628
Class T Shares		$	75		$	233		$	406		$	906

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Short-Term Bond Fund

Class D Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

The Board of Trustees of Janus Investment Fund approved a new management fee rate for Janus Henderson Short-Term Bond Fund (the “Fund”), effective December 14, 2018, that reduces the management fee rate paid by the Fund to Janus Capital Management LLC to 0.44%. A comparison of the Fund’s prior and new annual management fee rate schedule (expressed as an annual rate) is shown below.


PRIOR FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
First $300 Million Over $300 Million		0.64 0.54

NEW FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
All Asset Levels		0.44

In response to the above changes, the Fund’s Prospectuses are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)		Class D
Management Fees⁽¹⁾		0.44%
Other Expenses		0.21%
Total Annual Fund Operating Expenses⁽²⁾		0.65%
Fee Waiver⁽²⁾		0.07%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾		0.58%

(1)	Annual Fund Operating Expenses were restated, effective December 14, 2018, to reflect a reduction to the Management Fee paid by the Fund to Janus Capital.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.44% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

2.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:

EXAMPLE:

The following Example is based on expenses without waivers. The 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, reinvest all dividends and distributions, and then sell all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


	1 Year			3 Years			5 Years			10 Years
Class D Shares		$	66		$	208		$	362		$	810

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Large Cap Value Fund


Class A Shares	Class S Shares	Class N Shares
Class C Shares	Class I Shares	Class T Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Large Cap Value Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Management Fees (may adjust up or down)	0.47%	0.47%	0.47%	0.47%	0.47%	0.47%
Distribution/Services (12b-1) Fees	0.25%	1.00%	0.25%	None	None	None
Other Expenses	0.28%	0.30%	0.62%	0.25%	0.15%	0.41%
Total Annual Fund Operating Expenses⁽¹⁾	1.00%	1.77%	1.34%	0.72%	0.62%	0.88%
Fee Waiver⁽¹⁾	0.13%	0.14%	0.31%	0.08%	0.09%	0.10%
Total Annual Fund Operating Expenses After Fee Waiver⁽¹⁾	0.87%	1.63%	1.03%	0.64%	0.53%	0.78%

(1)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.70% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Large Cap Value Fund

Class D Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Large Cap Value Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class D
Management Fees (may adjust up or down)		0.47%
Other Expenses		0.31%
Total Annual Fund Operating Expenses⁽¹⁾		0.78%
Fee Waiver⁽¹⁾		0.11%
Total Annual Fund Operating Expenses After Fee Waiver⁽¹⁾		0.67%

(1)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, administrative services fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.70% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Global Unconstrained Bond Fund


Class A Shares	Class S Shares	Class N Shares
Class C Shares	Class I Shares	Class R Shares
	Class T Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Global Unconstrained Bond Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees	0.63%	0.63%	0.63%	0.63%	0.63%	0.63%	0.63%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	0.50%	None
Other Expenses	0.12%	0.13%	0.38%	0.12%	0.03%	0.39%	0.30%
Acquired Fund⁽¹⁾ Fees and Expenses	0.03%	0.03%	0.03%	0.03%	0.03%	0.03%	0.03%
Total Annual Fund Operating Expenses⁽²⁾	1.03%	1.79%	1.29%	0.78%	0.69%	1.55%	0.96%
Fee Waiver⁽²⁾	0.00%	0.00%	0.03%	0.00%	0.00%	0.04%	0.00%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾	1.03%	1.79%	1.26%	0.78%	0.69%	1.51%	0.96%

(1)

“Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights tables because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses), exceed 0.73% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Janus Investment Fund

Janus Henderson Global Unconstrained Bond Fund

Class D Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Global Unconstrained Bond Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class D
Management Fees		0.63%
Other Expenses		0.29%
Acquired Fund⁽¹⁾ Fees and Expenses		0.03%
Total Annual Fund Operating Expenses⁽²⁾		0.95%
Fee Waiver⁽²⁾		0.04%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾		0.91%

(1)

“Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights table because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.73% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Risk/Return:

rr_RiskReturnAbstract

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)

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Annual Fund Operating Expenses were restated, effective December 14, 2018, to reflect a reduction to the Management Fee paid by the Fund to Janus Capital.

Expense Example by Year [Heading]

rr_ExpenseExampleByYearHeading

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

If Shares are redeemed:

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class A

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.79%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.74%

^[2]

1 Year

rr_ExpenseExampleYear01

$ 329

5 Years

rr_ExpenseExampleYear05

678

Expense Example, No Redemption, By Year, Column [Text]

rr_ExpenseExampleNoRedemptionByYearColumnName

Class A Shares

3 Years

rr_ExpenseExampleNoRedemptionYear03

496

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,203

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.44%

^[1]

Other Expenses

rr_OtherExpensesOverAssets

0.13%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.05%

^[2]

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class C Shares

3 Years

rr_ExpenseExampleYear03

496

10 Years

rr_ExpenseExampleYear10

$ 1,867

1 Year

rr_ExpenseExampleNoRedemptionYear01

$ 160

5 Years

rr_ExpenseExampleNoRedemptionYear05

855

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class S

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.03%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.94%

^[2]

1 Year

rr_ExpenseExampleYear01

$ 105

5 Years

rr_ExpenseExampleYear05

569

Expense Example, No Redemption, By Year, Column [Text]

rr_ExpenseExampleNoRedemptionByYearColumnName

Class S Shares

3 Years

rr_ExpenseExampleNoRedemptionYear03

328

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,259

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.44%

^[1]

Other Expenses

rr_OtherExpensesOverAssets

0.13%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.05%

^[2]

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class I Shares

3 Years

rr_ExpenseExampleYear03

183

10 Years

rr_ExpenseExampleYear10

$ 714

1 Year

rr_ExpenseExampleNoRedemptionYear01

$ 58

5 Years

rr_ExpenseExampleNoRedemptionYear05

318

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class N

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.50%

^[2]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.44%

^[2]

1 Year

rr_ExpenseExampleYear01

$ 51

5 Years

rr_ExpenseExampleYear05

280

Expense Example, No Redemption, By Year, Column [Text]

rr_ExpenseExampleNoRedemptionByYearColumnName

Class N Shares

3 Years

rr_ExpenseExampleNoRedemptionYear03

160

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 628

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.44%

^[1]

Other Expenses

rr_OtherExpensesOverAssets

0.29%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.04%

^[2]

Expense Example, By Year, Column [Text]

rr_ExpenseExampleByYearColumnName

Class T Shares

3 Years

rr_ExpenseExampleYear03

233

10 Years

rr_ExpenseExampleYear10

$ 906

1 Year

rr_ExpenseExampleNoRedemptionYear01

$ 75

5 Years

rr_ExpenseExampleNoRedemptionYear05

406

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

Janus Investment Fund

Janus Henderson Short-Term Bond Fund

Class D Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

The Board of Trustees of Janus Investment Fund approved a new management fee rate for Janus Henderson Short-Term Bond Fund (the “Fund”), effective December 14, 2018, that reduces the management fee rate paid by the Fund to Janus Capital Management LLC to 0.44%. A comparison of the Fund’s prior and new annual management fee rate schedule (expressed as an annual rate) is shown below.


PRIOR FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
First $300 Million Over $300 Million		0.64 0.54

NEW FEE RATE
Average Daily Net Assets of the Fund		Contractual Investment Advisory Fee (%) (annual rate)
All Asset Levels		0.44

In response to the above changes, the Fund’s Prospectuses are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)		Class D
Management Fees⁽¹⁾		0.44%
Other Expenses		0.21%
Total Annual Fund Operating Expenses⁽²⁾		0.65%
Fee Waiver⁽²⁾		0.07%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾		0.58%

(1)	Annual Fund Operating Expenses were restated, effective December 14, 2018, to reflect a reduction to the Management Fee paid by the Fund to Janus Capital.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.44% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

2.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:

EXAMPLE:

The following Example is based on expenses without waivers. The 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, reinvest all dividends and distributions, and then sell all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses without waivers remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


	1 Year			3 Years			5 Years			10 Years
Class D Shares		$	66		$	208		$	362		$	810

Please retain this Supplement with your records.

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

November 1, 2019

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE:

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following Example is based on expenses without waivers. The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.44%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.65%

^[3]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.58%

^[3]

1 Year

rr_ExpenseExampleYear01

$ 66

5 Years

rr_ExpenseExampleYear05

362

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

Janus Investment Fund

Janus Henderson Large Cap Value Fund


Class A Shares	Class S Shares	Class N Shares
Class C Shares	Class I Shares	Class T Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Large Cap Value Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Management Fees (may adjust up or down)	0.47%	0.47%	0.47%	0.47%	0.47%	0.47%
Distribution/Services (12b-1) Fees	0.25%	1.00%	0.25%	None	None	None
Other Expenses	0.28%	0.30%	0.62%	0.25%	0.15%	0.41%
Total Annual Fund Operating Expenses⁽¹⁾	1.00%	1.77%	1.34%	0.72%	0.62%	0.88%
Fee Waiver⁽¹⁾	0.13%	0.14%	0.31%	0.08%	0.09%	0.10%
Total Annual Fund Operating Expenses After Fee Waiver⁽¹⁾	0.87%	1.63%	1.03%	0.64%	0.53%	0.78%

(1)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding any performance adjustments to management fees, the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.70% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

November 1, 2019

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.47%

^[4]

Other Expenses

rr_OtherExpensesOverAssets

0.28%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.13%

^[5]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class C

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.77%

^[5]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

1.63%

^[5]

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.47%

^[4]

Other Expenses

rr_OtherExpensesOverAssets

0.62%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.31%

^[5]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class I

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.72%

^[5]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.64%

^[5]

Risk/Return:

rr_RiskReturnAbstract

Management Fees

rr_ManagementFeesOverAssets

0.47%

^[4]

Other Expenses

rr_OtherExpensesOverAssets

0.15%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.09%

^[5]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class T

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.88%

^[5]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.78%

^[5]

Risk/Return:

rr_RiskReturnAbstract

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)

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class D

Other Expenses

rr_OtherExpensesOverAssets

0.31%

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.11%

^[6]

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

Janus Investment Fund

Janus Henderson Global Unconstrained Bond Fund


Class A Shares	Class S Shares	Class N Shares
Class C Shares	Class I Shares	Class R Shares
	Class T Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Global Unconstrained Bond Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class R	Class T
Management Fees	0.63%	0.63%	0.63%	0.63%	0.63%	0.63%	0.63%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	0.50%	None
Other Expenses	0.12%	0.13%	0.38%	0.12%	0.03%	0.39%	0.30%
Acquired Fund⁽¹⁾ Fees and Expenses	0.03%	0.03%	0.03%	0.03%	0.03%	0.03%	0.03%
Total Annual Fund Operating Expenses⁽²⁾	1.03%	1.79%	1.29%	0.78%	0.69%	1.55%	0.96%
Fee Waiver⁽²⁾	0.00%	0.00%	0.03%	0.00%	0.00%	0.04%	0.00%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾	1.03%	1.79%	1.26%	0.78%	0.69%	1.51%	0.96%

(1)

“Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights tables because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus/administrative fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses), exceed 0.73% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

November 1, 2019

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class A

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

none

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class C

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

none

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class S

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.03%

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class I

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

none

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class N

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

none

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class R

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

0.04%

^[8]

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class T

Distribution/Services (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.03%

^[7]

Fee Waiver

rr_FeeWaiverOrReimbursementOverAssets

none

^[8]

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

Janus Investment Fund

Janus Henderson Global Unconstrained Bond Fund

Class D Shares

Supplement dated December 14, 2018

to Currently Effective Prospectuses

Effective immediately, the Prospectuses for Janus Henderson Global Unconstrained Bond Fund (the “Fund”) are revised as follows:

1.	Under “Fees and Expenses of the Fund” in the Fund Summary section of the Fund’s Prospectuses, the following replaces the corresponding information:


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class D
Management Fees		0.63%
Other Expenses		0.29%
Acquired Fund⁽¹⁾ Fees and Expenses		0.03%
Total Annual Fund Operating Expenses⁽²⁾		0.95%
Fee Waiver⁽²⁾		0.04%
Total Annual Fund Operating Expenses After Fee Waiver⁽²⁾		0.91%

(1)

“Acquired Fund” refers to any underlying fund (including, but not limited to, exchange-traded funds) in which a fund invests or has invested during the period. Acquired fund fees and expenses are indirect expenses a fund may incur as a result of investing in shares of an underlying fund. To the extent that the Fund invests in Acquired Funds, the Fund’s “Total Annual Fund Operating Expenses” may not correlate to the “Ratio of gross expenses to average net assets” presented in the Financial Highlights table because that ratio includes only the direct operating expenses incurred by the Fund, not the indirect costs of investing in Acquired Funds.

(2)

Janus Capital has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding administrative services fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.73% until at least November 1, 2019. The contractual waiver may be terminated or modified prior to this date only at the discretion of the Board of Trustees.

Please retain this Supplement with your records.

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

November 1, 2019

Operating Expenses Column [Text]

rr_OperatingExpensesColumnName

Class D

Other Expenses

rr_OtherExpensesOverAssets

0.29%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.95%

^[10]

Total Annual Fund Operating Expenses After Fee Waiver

rr_NetExpensesOverAssets

0.91%

^[10]