<SUBMISSION>
<ACCESSION-NUMBER>0001338749-06-000119
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20061201
<FILING-DATE>20061205
<DATE-OF-FILING-DATE-CHANGE>20061205
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>POTLATCH CORP
<CIK>0001338749
<ASSIGNED-SIC>6798
<IRS-NUMBER>820156045
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>601 WEST RIVERSIDE AVENUE
<STREET2>SUITE 1100
<CITY>SPOKANE
<STATE>WA
<ZIP>99201
<PHONE>(509) 835-1500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>601 WEST RIVERSIDE AVENUE
<STREET2>SUITE 1100
<CITY>SPOKANE
<STATE>WA
<ZIP>99201
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Potlatch Holdings, Inc.
<DATE-CHANGED>20050914
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WEYERHAEUSER WILLIAM T
<CIK>0001056916
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-32729
<FILM-NUMBER>061257218
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>P O BOX 1278
<CITY>TACOMA
<STATE>WA
<ZIP>98401
<PHONE>2532728336
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>PO BOX 1278
<CITY>TACOMA
<STATE>WA
<ZIP>98401
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-12-01</periodOfReport>

    <issuer>
        <issuerCik>0001338749</issuerCik>
        <issuerName>POTLATCH CORP</issuerName>
        <issuerTradingSymbol>PCH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001056916</rptOwnerCik>
            <rptOwnerName>WEYERHAEUSER WILLIAM T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 W. RIVERSIDE AVE.</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>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>41.53</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-12-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1083.554</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>41.53</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1083.554</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2286.394</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Phantom stock units are credited to the reporting person's account on the transaction date in accordance with the provisions of the Potlatch Corporation Deferred Compensation Plan for Directors II and will be converted to cash and paid on a 1-for-1 basis with the issuer's common stock.</footnote>
        <footnote id="F2">The phantom stock units acquired represent an annual equity compensation award approved by the issuer's Board of Directors and granted to the reporting person.  The number of phantom stock units was determined by dividing the closing price of the issuer's common stock on the transaction date into the reporting person's award amount.</footnote>
        <footnote id="F3">The phantom stock units become payable in cash upon the reporting person's termination of service as a director of Potlatch Corporation.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Pamela A. Mull, Attorney-in-Fact</signatureName>
        <signatureDate>2006-12-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
