<SUBMISSION>
<ACCESSION-NUMBER>0001063083-05-000003
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20050816
<FILING-DATE>20050817
<DATE-OF-FILING-DATE-CHANGE>20050817
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ACACIA RESEARCH CORP
<CIK>0000934549
<ASSIGNED-SIC>3670
<IRS-NUMBER>954405754
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>7TH FLOOR
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
<PHONE>9494808300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>#
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>RYAN PAUL R
<CIK>0001063083
<STATE-OF-INCORPORATION>CA
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-26068
<FILM-NUMBER>051033241
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>949 480-8300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O ACACIA RESEARCH CORPORATION
<STREET2>500 NEWPORT CENTER DRIVE, 7TH FLOOR
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
</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>2005-08-16</periodOfReport>

    <issuer>
        <issuerCik>0000934549</issuerCik>
        <issuerName>ACACIA RESEARCH CORP</issuerName>
        <issuerTradingSymbol>ACTG/CBMX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001063083</rptOwnerCik>
            <rptOwnerName>RYAN PAUL R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>500 NEWPORT CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>7TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEWPORT BEACH</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92660</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Acacia Research - Acacia Technologies Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>35000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>492239</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Grant of Restricted Stock.</footnote>
        <footnote id="F2">7,000 shares are held indirectly by Reporting Person's daughter.  The Reporting Person disclaims beneficial ownership of the shares held by his daughter, and this report should not be deemed an admission that the Reporting Person is the beneficial owner of his daughter's shares for purposes of Section 16 or any other purpose.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Paul R. Ryan</signatureName>
        <signatureDate>2005-08-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
