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

    <schemaVersion>X0201</schemaVersion>

    <documentType>5</documentType>

    <periodOfReport>2003-12-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000719495</issuerCik>
        <issuerName>FIRST MANITOWOC BANCORP INC</issuerName>
        <issuerTradingSymbol>FWBW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001188176</rptOwnerCik>
            <rptOwnerName>WOJTA PAUL H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>402 NORTH 8TH ST</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MANITOWOC</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>54221</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP/Cashier/BSA Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>651</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>62231</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>460</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>62231</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares acquired pursuant to the Company's KSOP:  acquired 287 shares on 01/16/03 for $14.50 per share; acquired 28 shares on 02/05/03 for $14.50 per share; acquired 65 shares on 02/19/03 for $14.50 per share; acquired 7 shares on 02/25/03 for $14.50 per share; acquired 28 shares on 03/12/03 for $14.50 per share; acquired 57 shares on 04/11/03 for $15.10 per share; acquired 10 shares on 04/16/03 for $14.99 per share; acquired 10 shares on 04/17/03 for $14.50 per share; acquired 18 shares on 04/23/03 for $14.50 per share; acquired 64 shares on 07/16/03 for $14.66 per share; acquired 3 shares on 07/29/03 for $14.50 per share; acquired 28 shares on 08/11/03 for $14.50 per share; acquired 37 shares on 10/10/03 for $15.50 per share; acquired 5 shares on 10/13/03 for $15.10 per share; acquired 3 shares on 10/20/03 for $15.50 per share; acquired 1 share on 12/10/03 for $15.25 per share.</footnote>
        <footnote id="F2">Shares acquired pursuant to the Company's KSOP dividend reinvestment plan:  acquired 109 shares on 03/31/03 for $14.61 per share; acquired 111 shares on 06/25/03 for $14.50 per share; acquired 111 shares on 09/17/03 for $14.50 per share; acquired 129 shares on 12/18/03 for $15.25 per share.</footnote>
        <footnote id="F3">See footnote 2 for price.</footnote>
        <footnote id="F4">See footnote 1 for price.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Paul H. Wojta /s/ Rachel E. Wiegert POA</signatureName>
        <signatureDate>2004-02-06</signatureDate>
    </ownerSignature>
</ownershipDocument>

