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

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2005-06-02</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000910721</issuerCik>
        <issuerName>J JILL GROUP INC</issuerName>
        <issuerTradingSymbol>JILL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001328330</rptOwnerCik>
            <rptOwnerName>Fiske John III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>THE J. JILL GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>4 BATTERYMARCH PARK</rptOwnerStreet2>
            <rptOwnerCity>QUINCY</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02169</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, Human Resources</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Incentive Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>12.39</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-03-14</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-03-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Date indicated is date of grant. Option vests as follows: (a) one-third on March 14, 2006; (b) one-third on March 14, 2007; (c) one-third on March 14, 2008.</footnote>
        <footnote id="F2">Option vests in full upon death of holder while employed by the Company. Option is subject to accelerated vesting in event that a &quot;Qualified Sale&quot; occurs and immediately prior to such Qualified Sale holder is an employee of the Company. Immediately prior to such Qualified Sale the option shall become exercisable as to an additional one-third of the shares subject to the option. &quot;Qualified Sale&quot; means closing of a sale of all or substantially all of the assets or issued and outstanding capital stock of the Company, or the closing of a merger or consolidation involving the Company in which stockholders of the Company immediately before such merger or consolidation do not own immediately after such merger or consolidation capital stock or other equity interest of surviving corporation or entity representing more than fifty percent in voting power of capital stock or other equity interest of such surviving corporation or entity outstanding immediately after such merger or consolidation.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Linda L. Trudel, signed as Attorney-in-Fact under &quot;Power of Attorney and Confirming Statement&quot; attached hereto.</signatureName>
        <signatureDate>2005-06-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
