-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 V+mAIDw/iN3CWTQh0/mT3hMkMGy9yAqIwsRTceiSjYBe35dN8g4K8cooZl2p/A9J
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<SEC-DOCUMENT>0001140361-06-014930.txt : 20061026
<SEC-HEADER>0001140361-06-014930.hdr.sgml : 20061026
<ACCEPTANCE-DATETIME>20061026143825
ACCESSION NUMBER:		0001140361-06-014930
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20061024
FILED AS OF DATE:		20061026
DATE AS OF CHANGE:		20061026

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Shaffer Renee G
		CENTRAL INDEX KEY:			0001318306

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-18859
		FILM NUMBER:		061165454

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		405-225-5000

	MAIL ADDRESS:	
		STREET 1:		300 JOHNNY BENCH DRIVE
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73104

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SONIC CORP
		CENTRAL INDEX KEY:			0000868611
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-EATING PLACES [5812]
		IRS NUMBER:				731371046
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0831

	BUSINESS ADDRESS:	
		STREET 1:		300 JOHNNY BENCH DRIVE
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73104
		BUSINESS PHONE:		4052255000

	MAIL ADDRESS:	
		STREET 1:		300 JOHNNY BENCH DRIVE
		STREET 2:		4TH FLOOR
		CITY:			OKLAHOMA CITY
		STATE:			OK
		ZIP:			73104
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-10-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000868611</issuerCik>
        <issuerName>SONIC CORP</issuerName>
        <issuerTradingSymbol>SONC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001318306</rptOwnerCik>
            <rptOwnerName>Shaffer Renee G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>300 JOHNNY BENCH DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OKLAHOMA CITY</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>73104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President and CIO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Incentive Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>22.54</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-10-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1991</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-10-24</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1991</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1991</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-qualfied stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>22.54</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-10-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8787</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-10-24</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-10-24</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8787</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8787</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Renee G. Shaffer</signatureName>
        <signatureDate>2006-10-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----