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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 VqxkOiF7mOE8jYg3q31LrYDs9kcMzxxng0Qyk8VO49bmnGGAcmi99sGDj+ymTjOb
 hTBnu0KnnXubozeMqOpWxw==

<SEC-DOCUMENT>0001140361-09-011723.txt : 20090511
<SEC-HEADER>0001140361-09-011723.hdr.sgml : 20090511
<ACCEPTANCE-DATETIME>20090511174326
ACCESSION NUMBER:		0001140361-09-011723
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090505
FILED AS OF DATE:		20090511
DATE AS OF CHANGE:		20090511

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NELSON RICHARD A
		CENTRAL INDEX KEY:			0001135090
		STATE OF INCORPORATION:			CA

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30083
		FILM NUMBER:		09816498

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUALSTAR CORP
		CENTRAL INDEX KEY:			0000758938
		STANDARD INDUSTRIAL CLASSIFICATION:	MAGNETIC & OPTICAL RECORDING MEDIA [3695]
		IRS NUMBER:				953927330
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		3990-B HERITAGE OAK COURT
		CITY:			SIMI VALLEY
		STATE:			CA
		ZIP:			93063
		BUSINESS PHONE:		805-583-7744

	MAIL ADDRESS:	
		STREET 1:		3990-B HERITAGE OAK COURT
		CITY:			SIMI VALLEY
		STATE:			CA
		ZIP:			93063
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-05-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001135090</rptOwnerCik>
            <rptOwnerName>NELSON RICHARD A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3990 B HERITAGE OAK COURT</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SIMI VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93063</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP Engineering</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-05-05</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2009-05-05</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>81</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.25</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1885361</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Richard A. Nelson</signatureName>
        <signatureDate>2009-05-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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