<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-08-01</periodOfReport>

    <issuer>
        <issuerCik>0001051251</issuerCik>
        <issuerName>J CREW GROUP INC</issuerName>
        <issuerTradingSymbol>JCG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001452724</rptOwnerCik>
            <rptOwnerName>Lyons Jenna</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O J.CREW GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>770 BROADWAY</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10003</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Pres-Exec Creative Director</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <transactionDate>
                <value>2010-08-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7872</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>35.16</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>119304</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes 70,000 restricted shares of Common Stock, granted under an equity incentive plan of the issuer, of which 25,000 shares will vest (subject to the issuer's satisfaction of certain performance criteria over a three-year period commencing on December 17, 2007) on each of December 17, 2011 and December 17, 2012 and 20,000 shares will vest on April 15, 2011.</footnote>
    </footnotes>

    <remarks>Alice Givens is signing on behalf of Jenna Lyons pursuant to a power of attorney previously filed with the Securities and Exchange Commission.</remarks>

    <ownerSignature>
        <signatureName>Alice Givens pursuant to a power of attorney filed with the Commission</signatureName>
        <signatureDate>2010-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
