-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001316360-10-000101.txt : 20100929
<SEC-HEADER>0001316360-10-000101.hdr.sgml : 20100929
<ACCEPTANCE-DATETIME>20100929161308
ACCESSION NUMBER:		0001316360-10-000101
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100927
FILED AS OF DATE:		20100929
DATE AS OF CHANGE:		20100929

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			IHS Inc.
		CENTRAL INDEX KEY:			0001316360
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
		IRS NUMBER:				133769440
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1130

	BUSINESS ADDRESS:	
		STREET 1:		15 INVERNESS WAY EAST
		CITY:			ENGLEWOOD
		STATE:			CO
		ZIP:			80112
		BUSINESS PHONE:		303-790-0600

	MAIL ADDRESS:	
		STREET 1:		15 INVERNESS WAY EAST
		CITY:			ENGLEWOOD
		STATE:			CO
		ZIP:			80112

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			STEAD JERRE L
		CENTRAL INDEX KEY:			0001024219
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32511
		FILM NUMBER:		101096717

	BUSINESS ADDRESS:	
		STREET 1:		CONEXANT SYSTEMS, INC.
		STREET 2:		4311 JAMBOREE ROAD
		CITY:			NEWPORT BEACH
		STATE:			CA
		ZIP:			92660
		BUSINESS PHONE:		949-579-3000

	MAIL ADDRESS:	
		STREET 1:		MINDSPEED TECHNOLOGIES
		STREET 2:		4000 MACARTHUR BLVD., EAST TOWER
		CITY:			NEWPORT BEACH
		STATE:			CA
		ZIP:			92660
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-09-27</periodOfReport>

    <issuer>
        <issuerCik>0001316360</issuerCik>
        <issuerName>IHS Inc.</issuerName>
        <issuerTradingSymbol>IHS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001024219</rptOwnerCik>
            <rptOwnerName>STEAD JERRE L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IHS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>15 INVERNESS WAY EAST</rptOwnerStreet2>
            <rptOwnerCity>ENGELWOOD</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80112</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and Chairman of the Board</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-09-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>179811</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>258889</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by JMJS Group - II LLLP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Stephen Green, as Attorney-in-Fact for the Reporting Person</signatureName>
        <signatureDate>2010-09-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----