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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 GZrHBjx5i05bEu+x9BxqazmpqmKC1ayLJkXor+sui0Scfbko4GNNEi5k5gu8y3xs
 kbmSsao5XXqfGo8+VZSpZw==

<SEC-DOCUMENT>0001179110-05-000112.txt : 20050104
<SEC-HEADER>0001179110-05-000112.hdr.sgml : 20050104
<ACCEPTANCE-DATETIME>20050104101920
ACCESSION NUMBER:		0001179110-05-000112
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041231
FILED AS OF DATE:		20050104
DATE AS OF CHANGE:		20050104

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RAPLEY DAVID E
		CENTRAL INDEX KEY:			0001195192

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16615
		FILM NUMBER:		05504335

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		3038148762

	MAIL ADDRESS:	
		STREET 1:		720 EAST RIM ROAD
		CITY:			FRANKTOWN
		STATE:			CO
		ZIP:			80116

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LIBERTY MEDIA CORP /DE/
		CENTRAL INDEX KEY:			0001082114
		STANDARD INDUSTRIAL CLASSIFICATION:	CABLE & OTHER PAY TELEVISION SERVICES [4841]
		IRS NUMBER:				841288730
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		12300 LIBERTY BLVD.
		CITY:			ENGLEWOOD
		STATE:			CO
		ZIP:			80112
		BUSINESS PHONE:		7208755400

	MAIL ADDRESS:	
		STREET 1:		12300 LIBERTY BLVD.
		CITY:			ENGLEWOOD
		STATE:			CO
		ZIP:			80112
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-12-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001082114</issuerCik>
        <issuerName>LIBERTY MEDIA CORP /DE/</issuerName>
        <issuerTradingSymbol>L; LMC.B</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001195192</rptOwnerCik>
            <rptOwnerName>RAPLEY DAVID E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12300 LIBERTY BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ENGLEWOOD</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80112</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Series A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>569</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>569</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Rapley Consulting, Inc.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Series A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4129</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These shares of Series A common stock were received by the reporting person in payment of one half of his director fees, which equaled $6,250, for the quarter ended December 31, 2004, in accordance with the terms of the Liberty Media Corporation 2002 Nonemployee Director Incentive Plan.  The number of shares was determined based upon the closing market price of the Series A common stock on December 31, 2004, which was $10.98 per share, with cash distributed in lieu of fractional shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ David E. Rapley</signatureName>
        <signatureDate>2005-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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