<SUBMISSION>
<ACCESSION-NUMBER>0001144692-12-000002
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20120105
<FILING-DATE>20120109
<DATE-OF-FILING-DATE-CHANGE>20120109
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BRONSON STEVEN N
<CIK>0001000383
<STATE-OF-INCORPORATION>FL
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-30083
<FILM-NUMBER>12518461
</FILING-VALUES>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>QUALSTAR CORP
<CIK>0000758938
<ASSIGNED-SIC>3695
<IRS-NUMBER>953927330
<STATE-OF-INCORPORATION>CA
<FISCAL-YEAR-END>0630
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3990-B HERITAGE OAK COURT
<CITY>SIMI VALLEY
<STATE>CA
<ZIP>93063
<PHONE>805-583-7744
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3990-B HERITAGE OAK COURT
<CITY>SIMI VALLEY
<STATE>CA
<ZIP>93063
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BKF CAPITAL GROUP INC
<CIK>0000009235
<ASSIGNED-SIC>6282
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-30083
<FILM-NUMBER>12518462
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>ONE ROCKEFELLER PLAZA
<CITY>NEW YORK
<STATE>NY
<ZIP>10020
<PHONE>2123328400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>ONE ROCKEFELLER PLAZA
<CITY>NEW YORK
<STATE>NY
<ZIP>10020
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>BAKER FENTRESS & CO
<DATE-CHANGED>19970829
</FORMER-NAME>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>BAKER FENTRESS & CO ET AL
<DATE-CHANGED>19940714
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-01-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000758938</issuerCik>
        <issuerName>QUALSTAR CORP</issuerName>
        <issuerTradingSymbol>QBAK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000009235</rptOwnerCik>
            <rptOwnerName>BKF CAPITAL GROUP INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>225 N.E. MIZNER BOULEVARD, SUITE 2A</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOCA RATON</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33432</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001000383</rptOwnerCik>
            <rptOwnerName>BRONSON STEVEN N</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-01-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>305</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.88</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1816642</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-01-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>800</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.86</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1817442</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-01-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.86</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1817542</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares of Qualstar Corp. (Qualstar) common stock were purchased by BKF Capital Group, Inc. (BKF Captial) in an open market transaction.</footnote>
        <footnote id="F2">BKF Capital is the owner of 1,758,942 shares of Qualstar.  Steven N. Bronson as the Chairman and President of BKF Capital may be deemed to be the beneficial owner of the shares of Qualstar held by BKF Capital.  Mr. Bronson as the sole owner of BA Value Investors, LLC is the beneficial owner of an additional 57,700 shares of Qualstar held by BA Value Investors, LLC.</footnote>
        <footnote id="F3">BKF Capital is the owner of 1,759,742 shares of Qualstar.  Steven N. Bronson as the Chairman and President of BKF Capital may be deemed to be the benefcial owner of the shares of Qualstar held by BKF Capital.  Mr. Bronson as the sole owner of BA Value Investors, LLC is the beneficial owner of an additiional 57,700 shares of Qualstar held by BA Value Investors, LLC.</footnote>
        <footnote id="F4">BKF Capital is the owner of 1,759,842 shares of Qualstar.  Steven N. Bronson as the Chairman and President of BKF Capital may be deemed to be the beneficial owner of the shares of Qualstar held by BKF Captial.  Mr. Bronson as the sole owner of BA Value Investors, LLC is the beneficial owner of an additional 57,700 shares of Qualstar held by BA Value Investors, LLC.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Steven N. Bronson, President</signatureName>
        <signatureDate>2012-01-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Steven N. Bronson</signatureName>
        <signatureDate>2012-01-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
