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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-05-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000047111</issuerCik>
        <issuerName>HERSHEY CO</issuerName>
        <issuerTradingSymbol>HSY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000938543</rptOwnerCik>
            <rptOwnerName>HERSHEY TRUST CO TRUSTEE IN TRUST FOR MILTON HERSHEY SCHOOL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 MANSION ROAD EAST</rptOwnerStreet1>
            <rptOwnerStreet2>P O BOX 445</rptOwnerStreet2>
            <rptOwnerCity>HERSHEY</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>17033</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $1.00 par value</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2006-05-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>79679</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>56.5161</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12987852</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, $1.00 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>389000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Hershey Trust Company</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Class B Common Stock, $1.00 par value</value>
                <footnoteId id="F4"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>56.46</value>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, $1.00 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>60612012</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>60612012</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The repurchase of shares reported on this Form 4 was effected pursuant to a Rule 10b5-1 plan adopted in an agreement between the Issuer and the Reporting Person (the &quot;10b5-1 Plan&quot;). Pursuant to the 10b5-1 Plan, the Issuer has agreed to repurchase from the Reporting Person, on a weekly basis, through July 31, 2006, a number of shares of Common Stock equal to the product of the number of shares of Common Stock repurchased by the Issuer on the open market from shareholders other than the Reporting Person and affiliates of the Company (the &quot;Repurchased Shares&quot;) during the preceding calendar week (The &quot;Prior Week Shares&quot;) and 0.44.</footnote>
        <footnote id="F2">Pursuant to the 10b5-1 Plan, the per share price for shares of Common Stock repurchased by the Issuer is equal to the total consideration paid by the Issuer for the Prior Week Shares divided by the number of Repurchased Shares.</footnote>
        <footnote id="F3">Hershey Trust Company is wholly owned by the Milton Hershey School Trust and is trustee for the Milton Hershey School Trust.</footnote>
        <footnote id="F4">All shares of Class B common stock, $1.00 par value, are convertible share-for-share into common stock, $1.00 par value, at any time, and without payment other than for the fact of conversion.  There is no expiration date.</footnote>
        <footnote id="F5">Conversion price is the current market price ($56.46 represents the closing price on 05/30/2006).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Robert Vowler, President, Hershey Trust Company, Trustee for Milton Hershey School Trust</signatureName>
        <signatureDate>2006-05-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
