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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0000070858-09-000409.txt : 20091019
<SEC-HEADER>0000070858-09-000409.hdr.sgml : 20091019
<ACCEPTANCE-DATETIME>20091019171650
ACCESSION NUMBER:		0000070858-09-000409
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091015
FILED AS OF DATE:		20091019
DATE AS OF CHANGE:		20091019

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NUVEEN INSURED MUNICIPAL OPPORTUNITY FUND INC
		CENTRAL INDEX KEY:			0000878242
		IRS NUMBER:				363777460
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			1031

	BUSINESS ADDRESS:	
		STREET 1:		333 WEST WACKER DR
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3129178200

	MAIL ADDRESS:	
		STREET 1:		333 W WACKER
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BANK OF AMERICA CORP /DE/
		CENTRAL INDEX KEY:			0000070858
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-06379
		FILM NUMBER:		091126509

	BUSINESS ADDRESS:	
		STREET 1:		BANK OF AMERICA CORPORATE CENTER
		STREET 2:		100 N TRYON ST
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28255
		BUSINESS PHONE:		7043868486

	MAIL ADDRESS:	
		STREET 1:		BANK OF AMERICA CORPORATE CENTER
		STREET 2:		100 N TRYON ST
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28255

	FORMER NAME:	
		FORMER CONFORMED NAME:	BANKAMERICA CORP/DE/
		DATE OF NAME CHANGE:	19981022

	FORMER NAME:	
		FORMER CONFORMED NAME:	NATIONSBANK CORP
		DATE OF NAME CHANGE:	19920703

	FORMER NAME:	
		FORMER CONFORMED NAME:	NCNB CORP
		DATE OF NAME CHANGE:	19920107
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-10-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000878242</issuerCik>
        <issuerName>NUVEEN INSURED MUNICIPAL OPPORTUNITY FUND INC</issuerName>
        <issuerTradingSymbol>NIO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000070858</rptOwnerCik>
            <rptOwnerName>BANK OF AMERICA CORP /DE/</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BANK OF AMERICA CORPORATE CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>100 N TRYON ST</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28255</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>2009-10-15</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2009-10-15</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.89</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Subsidiary</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-10-15</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2009-10-15</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.82</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Subsidiary</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks>The transactions reported on this Form 4 were effected by Merrill Lynch, Pierce, Fenner &amp; Smith Incorporated, an indirect, wholly owned subsidiary of Bank of America Corporation.</remarks>

    <ownerSignature>
        <signatureName>Bank of America Corp, By:/s/ Angelina L Richardson, Vice President</signatureName>
        <signatureDate>2009-10-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Merrill Lynch, Pierce, Fenner &amp; Smith Incorporated, By:/s/ Robert M Shine, Attorney-in-Fact</signatureName>
        <signatureDate>2009-10-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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