<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-11-05</periodOfReport>

    <issuer>
        <issuerCik>0000866873</issuerCik>
        <issuerName>DEL MONTE FOODS CO</issuerName>
        <issuerTradingSymbol>DLM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001021567</rptOwnerCik>
            <rptOwnerName>ALLEN DAVID W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>DEL MONTE CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>ONE MARKET @ THE LANDMARK</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>SVP, Operations &amp; Supply Chain</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01, Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2009-11-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>296</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.78</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>125672</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents 295.94 deferred stock units issued under Del Monte Foods Company's 2002 Stock Incentive Plan pursuant to Del Monte's AIP Deferred Compensation Plan.  Each deferred stock unit issued in connection with the AIP Deferred Compensation Plan is credited with dividends which are converted into additional deferred stock units.  The deferred stock units reported herein reflect the additional deferred stock units credited in connection with the dividend the Company paid on 11/5/09.  Vesting of deferred stock units credited in connection with a dividend will follow the vesting of the underlying deferred stock units with respect to which such credited deferred stock units were calculated.</footnote>
        <footnote id="F2">Credited dividends were converted into additional deferred stock units based on the high/low average of the Company's stock on the transation date.</footnote>
        <footnote id="F3">Includes 64,071.24 deferred stock units and 41,600 Performance Accelerated Restricted Stock Units (PARS).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ James Potter, signed pursuant to power of attorney</signatureName>
        <signatureDate>2009-11-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
