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

    <documentType>4</documentType>
<periodOfReport>2003-12-02</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000093859</issuerCik>
        <issuerName>STEAK &amp; SHAKE CO</issuerName>
        <issuerTradingSymbol>SNS</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001249788</rptOwnerCik>
            <rptOwnerName>BEAR JAMES W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>36 S. PENNSYLVANIA</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 500</rptOwnerStreet2>
            <rptOwnerCity>INDIANAPOLIS</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46204</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>SVP; CFO</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable>
<nonDerivativeTransaction>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<transactionDate>
<value>2003-12-02</value>
</transactionDate>
<deemedExecutionDate>
</deemedExecutionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>5054</value>
</transactionShares>
<transactionPricePerShare>
<value>17.90</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode>
<value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>190448</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeHolding>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>97259</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value>See Footnote</value>
<footnoteId id="F1"/>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeHolding>
<nonDerivativeHolding>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>90000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value>See footnote</value>
<footnoteId id="F2"/>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeHolding>
</nonDerivativeTable>
<footnotes>
<footnote id="F1">These shares are held by Mr. Bear&#039;s spouse.</footnote>
<footnote id="F2">These shares are held in the Bear Family Limited Partnership, of which Mr. Bear is the Managing General Partner.  He disclaims any beneficial interest in these shares except to the extent of his pecuniary interest therein.</footnote>
</footnotes>
<remarks></remarks>
<ownerSignature>
<signatureName>David C. Milne, Attorney In Fact</signatureName>
<signatureDate>2003-12-03</signatureDate>
</ownerSignature>
</ownershipDocument>

