<SUBMISSION>
<ACCESSION-NUMBER>0001338749-06-000055
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20060323
<FILING-DATE>20060428
<DATE-OF-FILING-DATE-CHANGE>20060428
<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>GILLIS RUTH ANN M
<CIK>0001185158
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>001-32729
<FILM-NUMBER>06791787
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>10 SOUTH DEERBORN STREET
<STREET2>37TH FLOOR
<CITY>CHICAGO
<STATE>IL
<ZIP>80603
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2006-03-23</periodOfReport>

    <dateOfOriginalSubmission>2006-03-27</dateOfOriginalSubmission>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001185158</rptOwnerCik>
            <rptOwnerName>GILLIS RUTH ANN M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 WEST 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>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-03-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>207.7446</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3038.7446</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">As previously reported, the Issuer declared a special distribution to stockholders that was payable on March 31, 2006, in cash, shares of Potlatch common stock, or a combination of both, at the election of each stockholder.  The actual number of shares issued to the reporting person was also dependent upon the elections made by other stockholders and ownership limitations contained in the Issuer's Certificate of Incorporation.  As a result, the actual number of shares issued to the reporting person is less than previously reported.  This amendment reports the actual number of shares issued to the reporting person under the special distribution.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Malcolm A. Ryerse, Attorney-in-Fact</signatureName>
        <signatureDate>2006-04-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
