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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 VZTMjocwDJUUrwsdqnpgZmoeAbZOb7cTvEw24oIKqpPTilox17mQUIGhS6VEHKzn
 KgLYpmwVNBP1VwnNxr88sw==

<SEC-DOCUMENT>0001244059-03-000017.txt : 20031219
<SEC-HEADER>0001244059-03-000017.hdr.sgml : 20031219
<ACCEPTANCE-DATETIME>20031219105046
ACCESSION NUMBER:		0001244059-03-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031218
FILED AS OF DATE:		20031219

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SOUTHERN MICHIGAN BANCORP INC
		CENTRAL INDEX KEY:			0000703699
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				382407501
		STATE OF INCORPORATION:			MI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		51 W PEARL ST
		CITY:			COLDWATER
		STATE:			MI
		ZIP:			49036
		BUSINESS PHONE:		5172795500

	MAIL ADDRESS:	
		STREET 1:		51 W PEARL ST
		CITY:			COLDWATER
		STATE:			MI
		ZIP:			49036

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			JOHN H CASTLE
		CENTRAL INDEX KEY:			0001244083

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-49772
		FILM NUMBER:		031063942

	BUSINESS ADDRESS:	
		STREET 1:		51 W PEARL ST
		CITY:			COLDWATER
		STATE:			MI
		ZIP:			49036
		BUSINESS PHONE:		517-279-5500

	MAIL ADDRESS:	
		STREET 1:		51 W PEARL ST
		CITY:			COLDWATER
		STATE:			MI
		ZIP:			49036
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-18</periodOfReport>
    <issuer>
        <issuerCik>0000703699</issuerCik>
        <issuerName>SOUTHERN MICHIGAN BANCORP INC</issuerName>
        <issuerTradingSymbol>SOMC</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001244083</rptOwnerCik>
            <rptOwnerName>JOHN H CASTLE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>78 DOUGLAS AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>COLDWATER</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>49036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Chief Executive Officer</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock, par value $2.50</value></securityTitle><transactionDate><value>2003-12-18</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>400</value></transactionShares><transactionPricePerShare><value>20.95</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5600</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwners
hip><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Common Stock, par value $2.50</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>148</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By self as custodian for Patrick J. Castle.</value><footnoteId id="F1"/></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Stock Option - right to buy</value></securityTitle><conversionOrExercisePrice><value>16.55</value></conversionOrExercisePrice><exerciseDate><value>2005-03-17</value></exerciseDate><expirationDate><value>2013-03-17</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock, par value $2.50</value></underlyingSecurityTitle><underlyingSecuri
tyShares><value>1500</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1500</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes><footnote id="F1">This filing shall not be deemed an admission that the Reporting Person is, for the purposes of Section 16 of the Securities Exchange Act of 1934, as amended or otherwise, the beneficial owner of the equity securities held as custodian covered by this statement.</footnote></footnotes><remarks/><ownerSignature><signatureName>Phillip D. Torrence, attorney in  fact for John H. Castle.  Evidence of such authority to sign on behalf of such person is attached hereto.</signatureName><signatureDate>2003-12-18</signatureDate></ownerSignature></ownershipDocument>

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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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