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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-02-03</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001188659</rptOwnerCik>
            <rptOwnerName>POTTER JAMES</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, Gen Counsel &amp; Sec</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01, Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2011-02-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>154</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.95</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>85362</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents 153.92 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 that 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 2/3/11.  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 transaction date.</footnote>
        <footnote id="F3">Includes 32,553.33 deferred stock units, 17,200 Performance Accelerated Restricted Stock Units (PARS) and 6,700 Restricted Stock Units (RSU).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James Potter</signatureName>
        <signatureDate>2011-02-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
