-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Htf2rSCCuEwsYXsFR0BcL16EuO1eB2zs1dSwlzjCHuvksfcVgY0oZTlMtDVRWIth
 jO9AFlsr/p0pgM0Wd+ARZQ==

<SEC-DOCUMENT>0001179110-09-014737.txt : 20091023
<SEC-HEADER>0001179110-09-014737.hdr.sgml : 20091023
<ACCEPTANCE-DATETIME>20091023173333
ACCESSION NUMBER:		0001179110-09-014737
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091021
FILED AS OF DATE:		20091023
DATE AS OF CHANGE:		20091023

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			POWER ONE INC
		CENTRAL INDEX KEY:			0001042825
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRONIC COMPONENTS, NEC [3679]
		IRS NUMBER:				770420182
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		740 CALLE PLANO
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012
		BUSINESS PHONE:		8059878741

	MAIL ADDRESS:	
		STREET 1:		740 CALLE PLANO
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kambiz Hooshmand
		CENTRAL INDEX KEY:			0001321104

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-29454
		FILM NUMBER:		091135239

	BUSINESS ADDRESS:	
		STREET 1:		6290 SEQUENCE DRIVE
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		858-450-9333

	MAIL ADDRESS:	
		STREET 1:		6290 SEQUENCE DRIVE
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 3 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2009-10-21</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001042825</issuerCik>
        <issuerName>POWER ONE INC</issuerName>
        <issuerTradingSymbol>PWER</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001321104</rptOwnerCik>
            <rptOwnerName>Kambiz Hooshmand</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>740 CALLE PLANO</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMARILLO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93012</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>Kambiz Hooshmand</signatureName>
        <signatureDate>2009-10-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----