-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 LZKY9XpMx1gYv1L+ZruMDg==

<SEC-DOCUMENT>0000104889-11-000006.txt : 20110107
<SEC-HEADER>0000104889-11-000006.hdr.sgml : 20110107
<ACCEPTANCE-DATETIME>20110107113128
ACCESSION NUMBER:		0000104889-11-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110105
FILED AS OF DATE:		20110107
DATE AS OF CHANGE:		20110107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROSBERG GERALD M
		CENTRAL INDEX KEY:			0001123006

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-06714
		FILM NUMBER:		11516229

	MAIL ADDRESS:	
		STREET 2:		1150 15TH STREET NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20071

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WASHINGTON POST CO
		CENTRAL INDEX KEY:			0000104889
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-EDUCATIONAL SERVICES [8200]
		IRS NUMBER:				530182885
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1150 15TH ST NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20071
		BUSINESS PHONE:		2023346000

	MAIL ADDRESS:	
		STREET 1:		1150 15TH ST NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20071
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-01-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000104889</issuerCik>
        <issuerName>WASHINGTON POST CO</issuerName>
        <issuerTradingSymbol>WPO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001123006</rptOwnerCik>
            <rptOwnerName>ROSBERG GERALD M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2>1150 15TH STREET NW</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP-Planning and Dev.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-01-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>800</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4025</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Class B shares awarded as restricted stock under incentive plan.</footnote>
        <footnote id="F2">N/A</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Gerald M. Rosberg</signatureName>
        <signatureDate>2011-01-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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