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

    <documentType>4</documentType><periodOfReport>2004-01-21</periodOfReport>
    <issuer>
        <issuerCik>0000029924</issuerCik>
        <issuerName>DOW JONES &amp; CO INC</issuerName>
        <issuerTradingSymbol>DJ</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001189767</rptOwnerCik>
            <rptOwnerName>STEIGER PAUL E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 LIBERTY STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10281</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Managing Editor, WSJ</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option (Right to Buy)</value></securityTitle><conversionOrExercisePrice><value>52.65</value></conversionOrExercisePrice><transactionDate><value>2004-01-21</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>17500</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F2"/></exerciseDate><expirationDate><value>2014-01-21</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>17500</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>17500</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">This employee stock option was granted under the Dow Jones 2001 Long-Term Incentive Plan and includes a tandem SAR.</footnote><footnote id="F2">Grant of employee stock option to buy shares of common stock, one-third of shares exercisable beginning on the first anniversary of the date of grant, another one-third exercisable beginning on the second anniversary of the date of grant and the balance, beginning on the third anniversary of the date of grant.</footnote></footnotes><remarks/><ownerSignature><signatureName>Mia Israeli**Attorney in Fact</signatureName><signatureDate>2004-01-23</signatureDate></ownerSignature></ownershipDocument>

