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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-10-12</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>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Options To Buy</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>23.67</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-10-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>60000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-10-12</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-10-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>60000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>60000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Options To Buy</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.51</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-09</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-12-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>41600</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>41600</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Ms. Behrens was issued 10,000 shares of Common Stock for $0.05 per share (&quot;The Shares&quot;) on December 9, 2002, 2,000 shares were sold on April 1, 2004, leaving a balance of 8,000 shares.  The Shares may not be sold by Ms. Behrens with the consent of The Dress Barn, Inc. (&quot;the Company&quot;).  Such restrictions terminates as to 20% of the shares on each Succeeding December 9, 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 2001 Stock Incentive Plan</footnote>
        <footnote id="F3">Granted under the Company's 1995 Stock Option Plan.</footnote>
        <footnote id="F4">Exercisable in five equal installments with the first installment exercisable on the date indicated.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Vivian Behrens</signatureName>
        <signatureDate>2005-10-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
