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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-07-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000799166</issuerCik>
        <issuerName>MASSBANK CORP</issuerName>
        <issuerTradingSymbol>MASB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001134600</rptOwnerCik>
            <rptOwnerName>BRANDI GERARD H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MASSBANK CORP</rptOwnerStreet1>
            <rptOwnerStreet2>123 HAVEN STREET</rptOwnerStreet2>
            <rptOwnerCity>READING</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01867</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, Chairman &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock MASSBANK Corp</value>
            </securityTitle>
            <transactionDate>
                <value>2004-07-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.5625</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>227579.674</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Option(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.5625</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-07-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.5625</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1995-01-17</value>
            </exerciseDate>
            <expirationDate>
                <value>2005-01-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Exercise of stock options granted under the MASSBANK Corp 1986 Stock Option  Plan (4,804 shares) and the MASSBANK Corp 1994 Stock Incentive Plan (196 shares)</footnote>
        <footnote id="F2">Includes 158,739.224 shares owned directly by Gerard H. Brandi and his wife, Lynda Brandi; 23,528.507 shares owned directly by Gerard H. Brandi; and 26,431.2425 shares owned indirectly by Gerard H. Brandi under the MASSBANK Corp. Employee Stock Ownership Plan (ESOP)</footnote>
        <footnote id="F3">Also includes 17,378.147 shares owned by Lynda Brandi including 88.862 shares acquired on February 18, 2004 at $41.30 per share and 109.377 shares acquired on May 20, 2004 at $33.7567 per share pursuant to the reinvestment of dividends under the MASSBANK Corp Dividend Reinvestment Plan.  Mr. Brandi disclaims beneficial ownership of these shares and this report shall not be deemed an admission that Mr. Brandi is the beneficial owner.</footnote>
        <footnote id="F4">Also includes 1,502.553 shares owned indirectly by Gerard H. Brandi as the Custodian for minor children which total includes 8.057 shares acquired on February 18, 2004 at $41.30 per share and 11.023 shares acquired on May 20, 2004 at $33.7567 per share pursuant to the reinvestment of dividends under the MASSBANK Corp Dividend Reinvestment Plan.  Mr. Brandi disclaims beneficial ownership of these shares and the filing of this report shall not be deemed an admission that Mr. Brandi is the beneficial owner.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Gerard H. Brandi</signatureName>
        <signatureDate>2004-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>

