<SEC-DOCUMENT>0001140361-12-050643.txt : 20121211
<SEC-HEADER>0001140361-12-050643.hdr.sgml : 20121211
<ACCEPTANCE-DATETIME>20121211193036
ACCESSION NUMBER:		0001140361-12-050643
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20121201
FILED AS OF DATE:		20121211
DATE AS OF CHANGE:		20121211

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			OATES JAMES M
		CENTRAL INDEX KEY:			0001180238

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-08568
		FILM NUMBER:		121257527

	MAIL ADDRESS:	
		STREET 1:		C/O INVESTORS FINANCIAL SERVICES CORP
		STREET 2:		200 CLARENDON ST
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			JOHN HANCOCK BANK & THRIFT OPPORTUNITY FUND
		CENTRAL INDEX KEY:			0000925683
		IRS NUMBER:				043241844
		STATE OF INCORPORATION:			MA

	BUSINESS ADDRESS:	
		STREET 1:		C/O JOHN HANCOCK FUNDS
		STREET 2:		601 CONGRESS STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210
		BUSINESS PHONE:		617-663-3000

	MAIL ADDRESS:	
		STREET 1:		C/O JOHN HANCOCK FUNDS
		STREET 2:		601 CONGRESS STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HANCOCK JOHN BANK & THRIFT OPPORTUNITY FUND
		DATE OF NAME CHANGE:	19940728

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HANCOCK JOHN REGIONAL BANK & THRIFT FUND
		DATE OF NAME CHANGE:	19940620
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2012-12-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000925683</issuerCik>
        <issuerName>JOHN HANCOCK BANK &amp; THRIFT OPPORTUNITY FUND</issuerName>
        <issuerTradingSymbol>BTO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001180238</rptOwnerCik>
            <rptOwnerName>OATES JAMES M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O JOHN HANCOCK FUNDS</rptOwnerStreet1>
            <rptOwnerStreet2>601 CONGRESS STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02210</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Trustee of the Fund</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>common shares of beneficial interest</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>646</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ James M. Oates</signatureName>
        <signatureDate>2012-12-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
