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

    <documentType>4</documentType><periodOfReport>2003-10-09</periodOfReport>
    <issuer>
        <issuerCik>0000032166</issuerCik>
        <issuerName>ELECTRO RENT CORP</issuerName>
        <issuerTradingSymbol>elrc</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001163534</rptOwnerCik>
            <rptOwnerName>KEARNS JOSEPH J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>23852 PACIFIC COAST HWY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 754</rptOwnerStreet2>
            <rptOwnerCity>MALIBU</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90265</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Non-Employee Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>13.45</value></conversionOrExercisePrice><transactionDate><value>2003-10-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>2000</value></transactionShares><transactionPricePerShare><footnoteId id="F1"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F2"/></exerciseDate><expirationDate><value>2008-10-09</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>2000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Grant of derivative security.</footnote><footnote id="F2">The option vests in two annual installmetns beginning on October 9, 2004.</footnote></footnotes><remarks/><ownerSignature><signatureName>Joseph J. Kearns</signatureName><signatureDate>2003-10-09</signatureDate></ownerSignature></ownershipDocument>

