<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-01</periodOfReport>
    <issuer>
        <issuerCik>0001058289</issuerCik>
        <issuerName>LEXAR MEDIA INC</issuerName>
        <issuerTradingSymbol>LEXR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001234046</rptOwnerCik>
            <rptOwnerName>WHITAKER ERIC S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LEXAR MEDIA, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>47421 BAYSIDE PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>FREMONT</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>VP, General Counsel &amp;Secretary</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-01</value></transactionDate><deemedExecutionDate><value>2003-12-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>8334</value></transactionShares><transactionPricePerShare><value>.92</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>37879</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-01</value></transactionDate><deemedExecutionDate><value>2003-12-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>1666</value></transactionShares><transactionPricePerShare><value>2.62</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>39545</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-01</value></transactionDate><deemedExecutionDate><value>2003-12-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>21.815</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>29545</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option (Right to Purchase)</value></securityTitle><conversionOrExercisePrice><value>.92</value></conversionOrExercisePrice><transactionDate><value>2003-12-01</value></transactionDate><deemedExecutionDate><value>2003-12-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>8334</value></transactionShares><transactionPricePerShare><value>.92</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2002-02-28</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2011-08-29</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>8334</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>175000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stock Option (Right to Purchase)</value></securityTitle><conversionOrExercisePrice><value>2.62</value></conversionOrExercisePrice><transactionDate><value>2003-12-01</value></transactionDate><deemedExecutionDate><value>2003-12-01</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>1666</value></transactionShares><transactionPricePerShare><value>2.62</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2002-09-26</value><footnoteId id="F3"/></exerciseDate><expirationDate><value>2012-03-25</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1666</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>58751</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">As of December 1, 2003, 1,771 shares were subject to the Issuer's right to repurchase such shares at the original price paid by Mr. Whitaker in the event Mr. Whitaker's relationship with the Issuer is terminated.  The Issuer's repurchase right lapsed as to twenty-five percent (25%) of the shares on December 21, 2000 and lapses with respect to an additional 1/48th of the total number of shares on each succeeding month thereafter until fully vested.</footnote><footnote id="F2">As of December 1, 2003, no further shares are vested or exercisable.  Twelve and one-half percent (12.5%) of the shares subject to the grant vested and became exercisable on February 28, 2002, and an additional 1/48th of the total number of shares vest and become exercisable on the 28th day of each succeeding month thereafter until fully vested.</footnote><footnote id="F3">As of December 31, 2003, 417 shares are vested and exercisable.  Twelve and one-half percent (12.5%) of the shares subject to the grant vested and became exercisable on September 26, 2002, and an additional 1/48th of the total number of shares vest and become exercisable on the 26th day of each succeeding month thereafter until fully vested.</footnote></footnotes><remarks/><ownerSignature><signatureName>Eric S. Whitaker</signatureName><signatureDate>2003-12-03</signatureDate></ownerSignature></ownershipDocument>

