<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType><periodOfReport>2003-11-01</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000079716</issuerCik>
        <issuerName>POTLATCH CORP</issuerName>
        <issuerTradingSymbol>PCH</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001185158</rptOwnerCik>
            <rptOwnerName>GILLIS RUTH ANN M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 W. RIVERSIDE AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1100</rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99201</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>No securities beneficially owned</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><footnotes/><remarks/><ownerSignature><signatureName>Malcolm A. Ryerse, Attorney-in-fact</signatureName><signatureDate>2003-10-30</signatureDate></ownerSignature></ownershipDocument>

