<SUBMISSION>
<ACCESSION-NUMBER>0001293301-09-000011
<TYPE>3
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090610
<FILING-DATE>20090622
<DATE-OF-FILING-DATE-CHANGE>20090622
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LEVAN ALAN B
<CIK>0001199943
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3
<ACT>34
<FILE-NUMBER>000-26396
<FILM-NUMBER>09904315
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>2100 W. CYPRESS CREEK RD.
<CITY>FT LAUDERDALE
<STATE>FL
<ZIP>33309
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>BENIHANA INC
<CIK>0000935226
<ASSIGNED-SIC>5812
<IRS-NUMBER>650538630
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0330
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>8685 NW 53RD TERRACE
<CITY>MIAMI
<STATE>FL
<ZIP>33166
<PHONE>3055930770
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>8685 NW 53RD TERRACE
<CITY>MIAMI
<STATE>FL
<ZIP>33166
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2009-06-10</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000935226</issuerCik>
        <issuerName>BENIHANA INC</issuerName>
        <issuerTradingSymbol>BNHN/BNHNA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001199943</rptOwnerCik>
            <rptOwnerName>LEVAN ALAN B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BENIHANA INC.</rptOwnerStreet1>
            <rptOwnerStreet2>8685 N.W. 53RD TERRACE</rptOwnerStreet2>
            <rptOwnerCity>MIAMI</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33166</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">BFC Financial Corporation (&quot;BFC&quot;) owns 800,000 shares of the issuer's Series B Convertible Preferred Stock, which is convertible at any time in BFC's discretion into an aggregate of 1,578,943 shares of the issuer's Common Stock.  Mr. Levan is the Chairman, Chief Executive Officer and President of, and may be deemed to control, BFC, but Mr. Levan disclaims any pecuniary interest in or beneficial ownership of the shares of the issuer's Series B Convertible Preferred Stock owned by BFC.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Alan B. Levan</signatureName>
        <signatureDate>2009-06-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
