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

    <documentType>4</documentType><periodOfReport>2003-10-27</periodOfReport>
    <issuer>
        <issuerCik>0001058289</issuerCik>
        <issuerName>LEXAR MEDIA INC</issuerName>
        <issuerTradingSymbol>LEXR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001234045</rptOwnerCik>
            <rptOwnerName>STANG ERIC B</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>1</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>President and CEO </officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-10-27</value></transactionDate><deemedExecutionDate><value>2003-10-27</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>2.69</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>75477</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-10-27</value></transactionDate><deemedExecutionDate><value>2003-10-27</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>20.0472</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>65477</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>2.69</value></conversionOrExercisePrice><transactionDate><value>2003-10-27</value></transactionDate><deemedExecutionDate><value>2003-10-27</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>2.69</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-02-12</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2012-08-11</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>10000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>829790</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">As of October 27, 2003, 16,667 shares were subject to the Issuer's right to repurchase such shares at the original purchase price paid by Mr. Stang in the event Mr. Stang's relationship with the Issuer is terminated.  The Issuer's repurchase right lapsed as to twenty-five percent (25%) of the shares on November 8, 2000 and lapses with respect to an additional 1/48th of the total number of shares on the 8th day of each succeeding month thereafter until fully vested.</footnote><footnote id="F2">As of October 27, 2003, 227,706 shares are vested and exercisable.  Twelve and one-half percent (12.5%) of the shares subject to the grant vested and became exercisable on February 12, 2003, and an additional 1/48th of the total number of shares vest and become exercisable on the 12th day of each succeeding month thereafter until fully vested.</footnote></footnotes><remarks/><ownerSignature><signatureName>Eric B. Stang</signatureName><signatureDate>2003-10-29</signatureDate></ownerSignature></ownershipDocument>

