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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-06-27</periodOfReport>

    <issuer>
        <issuerCik>0000717724</issuerCik>
        <issuerName>DRESS BARN INC</issuerName>
        <issuerTradingSymbol>DBRN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001024753</rptOwnerCik>
            <rptOwnerName>BEHRENS VIVIAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE DRESS BARN, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>30 DUNNIGAN DRIVE</rptOwnerStreet2>
            <rptOwnerCity>SUFFERN</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.12</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Buy</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.76</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-09</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-12-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>73200</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>73200</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Buy</value>
                <footnoteId id="F4"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.84</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-10-12</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-10-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>120000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>120000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted stock granted under the Company's 1995 Stock Plan.   The Shares may not be sold by Ms. Behrens without the consent of The Dress Barn, Inc. (&quot;the Company&quot;).  Such restrictions terminate as to 20% of the shares on each succeeding December 9, until December 9, 2007, provided Ms. Behrens is employed by the Company on such dates (the Shares as to which such provisions have terminated are referred to as &quot;Vested Shares&quot;).</footnote>
        <footnote id="F2">Granted under the Company's  1995 Stock Option Plan.</footnote>
        <footnote id="F3">Exercisable in five equal installments with the first installment exercisable on the date indicated.</footnote>
        <footnote id="F4">Granted under the Company's 2001 Stock Incentive Plan</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Vivian Behrens</signatureName>
        <signatureDate>2006-06-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
