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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-10-26</periodOfReport>

    <issuer>
        <issuerCik>0001341439</issuerCik>
        <issuerName>ORACLE CORP</issuerName>
        <issuerTradingSymbol>ORCL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001468342</rptOwnerCik>
            <rptOwnerName>Kurian Thomas</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O DELPHI ASSET MANAGEMENT CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>5525 KIETZKE LANE, SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>RENO</rptOwnerCity>
            <rptOwnerState>NV</rptOwnerState>
            <rptOwnerZipCode>89511</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>President-Product Development</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-10-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1623.528</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1623.528</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>416272.591</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents PSUs distributed</footnote>
        <footnote id="F2">Each restricted stock unit represents the right to receive, at settlement, one share of common stock.</footnote>
        <footnote id="F3">Each restricted stock unit represents the right to receive, at settlement, one share of common stock.</footnote>
        <footnote id="F4">Represents dividend equivalents accrued with respect to earned performance stock units the reporting person has elected to defer.  The number of dividend equivalents reported was calculated using Oracle's closing stock price on July 27, 2016 ($40.93), the date on which dividends were paid on Oracle's common stock.</footnote>
    </footnotes>

    <remarks>Amendment being filed to report a stock option grant inadvertently omitted from the original filing.</remarks>

    <ownerSignature>
        <signatureName>/s/ Lori A. Clancy by Lori A. Clancy, Attorney in Fact for Thomas Kurian (POA Filed 01/28/2016)</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
