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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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 AtpZfqgbauzazQ8OZtybfQ==

<SEC-DOCUMENT>0000811612-08-000027.txt : 20080605
<SEC-HEADER>0000811612-08-000027.hdr.sgml : 20080605
<ACCEPTANCE-DATETIME>20080605153802
ACCESSION NUMBER:		0000811612-08-000027
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080604
FILED AS OF DATE:		20080605
DATE AS OF CHANGE:		20080605

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COMMERCE GROUP INC /MA
		CENTRAL INDEX KEY:			0000811612
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				042599931
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		211 MAIN ST
		CITY:			WEBSTER
		STATE:			MA
		ZIP:			01570
		BUSINESS PHONE:		5089439000

	MAIL ADDRESS:	
		STREET 1:		211 MAIN STREET
		STREET 2:		211 MAIN STREET
		CITY:			WEBSTER
		STATE:			MA
		ZIP:			01570

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Moynihan Cathleen M
		CENTRAL INDEX KEY:			0001335287

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13672
		FILM NUMBER:		08882960

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		508-643-0465

	MAIL ADDRESS:	
		STREET 1:		145 OAKRIDGE AVENUE
		CITY:			NORTH ATTLEBORO
		STATE:			MA
		ZIP:			02760
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-06-04</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000811612</issuerCik>
        <issuerName>COMMERCE GROUP INC /MA</issuerName>
        <issuerTradingSymbol>CGI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001335287</rptOwnerCik>
            <rptOwnerName>Moynihan Cathleen M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>145 OAKRIDGE AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORTH ATTLEBORO</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02760</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>17609</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.7</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1270</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.7</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Each share was converted into the right to receive $36.70 per share pursuant to the Agreement and Plan of Merger, dated as of October 30, 2007, among The Commerce Group, Inc., Mapfre S.A. and Magellan Acquisition Corp. (the &quot;Merger Agreement&quot;).</footnote>
        <footnote id="F2">The reporting person indirectly beneficially owns 1,270 shares that are held by the Employee Stock Ownership Plan of The Commerce Group, Inc., which number of shares is calculated based on the units that have been credited to the reporting person as a participant in the ESOP and is subject to adjustment from time to time due, in part, to the unit value and the price per share of the common stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Cathleen M. Moynihan</signatureName>
        <signatureDate>2008-06-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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