<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>5</documentType>
<periodOfReport>2003-09-30</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000108312</issuerCik>
        <issuerName>WOODWARD GOVERNOR CO</issuerName>
        <issuerTradingSymbol>WGOV</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001113708</rptOwnerCik>
            <rptOwnerName>MANNING CAROL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5001 N. SECOND STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROCKFORD</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>61111</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Corporate Secretary</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Woodward Governor Company Common Stock</value>
</securityTitle>
<transactionDate><value>2003-09-30</value>
</transactionDate>
<transactionCoding><transactionFormType>5</transactionFormType>
<transactionCode>J</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>40</value>
</transactionShares>
<transactionPricePerShare><footnoteId id="F1"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>1749</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Woodward Governor Company Common Stock</value>
</securityTitle>
<transactionDate><value>2003-09-30</value>
</transactionDate>
<transactionCoding><transactionFormType>5</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>210</value>
</transactionShares>
<transactionPricePerShare><footnoteId id="F2"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>5057</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>Stock Plan</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Woodward Governor Company Common Stock</value>
</securityTitle>
<transactionDate><value>2003-09-30</value>
</transactionDate>
<transactionCoding><transactionFormType>5</transactionFormType>
<transactionCode>J</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>38</value>
</transactionShares>
<transactionPricePerShare><footnoteId id="F1"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>1662</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>Husband's IRA</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable></derivativeTable>
<footnotes><footnote id="F1">Annual update for automatic reinvestment of dividends</footnote>
<footnote id="F2">Annual update for company stock plan contributions</footnote>
</footnotes>
<ownerSignature><signatureName>Carol J. Manning</signatureName>
<signatureDate>2003-11-12</signatureDate>
</ownerSignature>
</ownershipDocument>

