<SUBMISSION>
<ACCESSION-NUMBER>0001338749-06-000024
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20060223
<FILING-DATE>20060227
<DATE-OF-FILING-DATE-CHANGE>20060227
<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>SIEGEL L PENDLETON
<CIK>0001180479
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-32729
<FILM-NUMBER>06647174
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>601 W RIVERSIDE AVE SUITE 1100
<CITY>SPOKANE
<STATE>WA
<ZIP>99201
<PHONE>5098351512
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>601 W RIVERSIDE AVE SUITE 1100
<CITY>SPOKANE
<STATE>WA
<ZIP>99201
</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>2006-02-23</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001180479</rptOwnerCik>
            <rptOwnerName>SIEGEL L PENDLETON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 W. RIVERSIDE AVENUE, SUITE 1100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99201</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman of the Board</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-02-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5375.98</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5375.98</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42171.339</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The conversion of the non-derivative security will occur on a one-for-one basis.</footnote>
        <footnote id="F2">The reporting person elected to defer receipt of 50% of his bonus award into an account in the form of phantom stock units. The phantom stock units will be converted to cash and paid on the dates pre-selected by the reporting person.  The bonus award was granted to the reporting person in accordance with the Potlatch Corporation Management Performance Award Plan, pursuant to the stockholder-approved Potlatch Corporation 2000 Stock Incentive Plan.  Transaction is exempt under Rule 16(b)-3, as the award was granted by a Committee of the Board of Directors composed solely of non-employee Directors.</footnote>
        <footnote id="F3">The bonus award granted to the reporting person was neither a purchase nor a sale of a derivative security, therefore there is no price to report.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Malcolm A. Ryerse, Attorney-in-fact</signatureName>
        <signatureDate>2006-02-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
