<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-12-29</periodOfReport>

    <issuer>
        <issuerCik>0001169770</issuerCik>
        <issuerName>FIRST PACTRUST BANCORP INC</issuerName>
        <issuerTradingSymbol>BANC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001506599</rptOwnerCik>
            <rptOwnerName>Liu Chang</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FIRST PACTRUST BANCORP INC.</rptOwnerStreet1>
            <rptOwnerStreet2>610 BAY BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>CHULA VISTA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>91910</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>EVP AND CHIEF LENDING OFFICER</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4512</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8210</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks>1. Represents grant of restricted stock to the reporting person pursuant to the issuer's 2011 Omnibus Incentive Plan. One-third of the shares granted vested on December 31, 2011, with the balanced scheduled to vest on the subsequent two years.
2. Amount of Securities Beneficially Owned may/will include shares obtained through the issuer's Dividend Reinvestment Plan (DRIP).</remarks>

    <ownerSignature>
        <signatureName>/s/ Richard Herrin</signatureName>
        <signatureDate>2012-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
