<SUBMISSION>
<ACCESSION-NUMBER>0001144692-11-000012
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20110824
<FILING-DATE>20110826
<DATE-OF-FILING-DATE-CHANGE>20110826
<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>111061000
</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>111061001
</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>2011-08-24</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 NE MIZNER BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</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>2011-08-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6400</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1636339</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-08-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1638339</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-08-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4000</value>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1642339</value>
                    <footnoteId id="F6"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares of Qualstar Corp. (Qualstar) were purchased by BKF Capital Group, Inc. (BKF Capital) in an open market transaction.</footnote>
        <footnote id="F2">BKF Capital is the owner of 1,578,639 shares of Qualstar.  Steven N. Bronson as the Chairman and President of BKF Captial may be deemed the beneficial owner of the shares of Qualstar held by BKF Captial.  Mr. Bronson, as the sole member 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">These shares of Qualstar were purchased by BKF Capital in an open market transaction.</footnote>
        <footnote id="F4">BKF Captial is the owner of 1,580,639 shares of Qualstar. Steven N. Bronson as the Chairman and President of BKF Capital may be deemed to the beneficial owner of the shares of Qualstar held by BKF Capital.  Mr. Bronson, as the sole member 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="F5">These shares of Qualstar were purchased by BKF Capital in an open market transaction.</footnote>
        <footnote id="F6">BKF Capital is the owner of 1,584,639 shares of Qualstar.  Steven N. Bronson as the Chairman and President of BKF Captial may be deemed to be the beneficial owner of the shares of Qualstar held by BKF Capital.  Mr. Brosnon, 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>2011-08-26</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Steven N. Bronson</signatureName>
        <signatureDate>2011-08-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
