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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-05-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000737210</issuerCik>
        <issuerName>LNB BANCORP INC</issuerName>
        <issuerTradingSymbol>LNBB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001316586</rptOwnerCik>
            <rptOwnerName>KLIMAS DANIEL E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>LORAIN NATIONAL BANK</rptOwnerStreet1>
            <rptOwnerStreet2>457 BROADWAY</rptOwnerStreet2>
            <rptOwnerCity>LORAIN</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44052</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and C.E.O.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>LNB Bancorp, Inc. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-05-07</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2010-05-07</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.21</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>36545</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Mr. Klimas's total shares of 36545 are comprised of the following:
1.  25000 shares of restricted stock granted under 2006 Stock Incentive Plan.  Shares vest in %50 increments on the 2nd and 3rd anniversaries of the date of grant.
2.  7742 shares held directly by Mr. Klimas.
3.  3803 shares held in the Lorain National Bank 401(K) plan - FBO Daniel Klimas.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Daniel E. Klimas</signatureName>
        <signatureDate>2010-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
