<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4/A</documentType>
<periodOfReport>2003-11-06</periodOfReport>
<dateOfOriginalSubmission>2003-11-06</dateOfOriginalSubmission>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001021113</issuerCik>
        <issuerName>GUITAR CENTER INC</issuerName>
        <issuerTradingSymbol>GTRC</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001106651</rptOwnerCik>
            <rptOwnerName>THOMAS LAWRENCE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GUITAR CENTER, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>5795 LINDERO CANYON ROAD</rptOwnerStreet2>
            <rptOwnerCity>WESTLAKE VILLAGE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>91362</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Chairman and Co-CEO</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-11-06</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>25000</value>
</transactionShares>
<transactionPricePerShare><value>31</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>392931</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>by trusts</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-11-06</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>50000</value>
</transactionShares>
<transactionPricePerShare><value>11</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>392931</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>by trusts</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-11-06</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>50000</value>
</transactionShares>
<transactionPricePerShare><value>30</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>392931</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>by trusts</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>11</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-11-06</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>50000</value>
</transactionShares>
<transactionPricePerShare><value>30</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>1997-06-30</value>
</exerciseDate>
<expirationDate><value>2006-06-03</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>50000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>347985</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
</derivativeTable>
<footnotes></footnotes>
<ownerSignature><signatureName>Erick G. Mason, Attorney-in-fact</signatureName>
<signatureDate>2003-11-07</signatureDate>
</ownerSignature>
</ownershipDocument>

