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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-08-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001231639</rptOwnerCik>
            <rptOwnerName>ELEK GARY J</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>C.F.O.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>LNB Bancorp, Inc. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-08-18</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2010-08-18</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>4.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14675</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Mr. Elek's shares of 14675 are comprised of the following:  1.  10000 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.  3500 shares held directly by Mr. Elek.  3.  1175 shares held in the Lorain National Bank 401(k) plan - FBO Gary Elek.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Gary J. Elek</signatureName>
        <signatureDate>2010-08-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
