-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 SenkevIMGxlXG+2JIsavPw+tAm4vE1oXSvbkYpM+ka4ZOxE1Q3TRQbSTxdhi3gdU
 i8z4kNsfpbapy/uz43x4Kg==

<SEC-DOCUMENT>0001302018-08-000006.txt : 20080304
<SEC-HEADER>0001302018-08-000006.hdr.sgml : 20080304
<ACCEPTANCE-DATETIME>20080304150723
ACCESSION NUMBER:		0001302018-08-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080303
FILED AS OF DATE:		20080304
DATE AS OF CHANGE:		20080304

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DECOCCO PHILIP J
		CENTRAL INDEX KEY:			0001256018

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20206
		FILM NUMBER:		08663268

	BUSINESS ADDRESS:	
		STREET 1:		886 STURGES HIGHWAY
		CITY:			WESTPORT
		STATE:			CT
		ZIP:			06880

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PERCEPTRON INC/MI
		CENTRAL INDEX KEY:			0000887226
		STANDARD INDUSTRIAL CLASSIFICATION:	OPTICAL INSTRUMENTS & LENSES [3827]
		IRS NUMBER:				382381442
		STATE OF INCORPORATION:			MI
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		47827 HALYARD DRIVE
		CITY:			PLYMOUTH
		STATE:			MI
		ZIP:			48170-2461
		BUSINESS PHONE:		3134144816

	MAIL ADDRESS:	
		STREET 1:		47827 HALYARD DRIVE
		CITY:			PLYMOUTH
		STATE:			MI
		ZIP:			48170-2461
</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>2008-03-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000887226</issuerCik>
        <issuerName>PERCEPTRON INC/MI</issuerName>
        <issuerTradingSymbol>PRCP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001256018</rptOwnerCik>
            <rptOwnerName>DECOCCO PHILIP J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>47827 HALYARD DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PLYMOUTH</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48170</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-03-03</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1036</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.58</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>38951</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On March 3, 2008, the reporting person received 1,036 shares in lieu of his Board Compensation pursuant to the Directors Stock Purchase Rights under the 2004 Stock Incentive Plan, an exempt plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Sylvia M Smith on behalf of Philip J DeCocco</signatureName>
        <signatureDate>2008-03-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----