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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001127602-10-020059.txt : 20100729
<SEC-HEADER>0001127602-10-020059.hdr.sgml : 20100729
<ACCEPTANCE-DATETIME>20100729114607
ACCESSION NUMBER:		0001127602-10-020059
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100727
FILED AS OF DATE:		20100729
DATE AS OF CHANGE:		20100729

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MacDonald Robert D III
		CENTRAL INDEX KEY:			0001304501

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-03285
		FILM NUMBER:		10976799

	MAIL ADDRESS:	
		STREET 1:		3M CENTER
		CITY:			ST. PAUL
		STATE:			MN
		ZIP:			55144

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			3M CO
		CENTRAL INDEX KEY:			0000066740
		STANDARD INDUSTRIAL CLASSIFICATION:	SURGICAL & MEDICAL INSTRUMENTS & APPARATUS [3841]
		IRS NUMBER:				410417775
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3M CENTER
		STREET 2:		BLDG. 220-11W-02
		CITY:			ST PAUL
		STATE:			MN
		ZIP:			55144-1000
		BUSINESS PHONE:		6517332204

	MAIL ADDRESS:	
		STREET 1:		3M CENTER
		STREET 2:		BLDG. 220-11W-02
		CITY:			ST. PAUL
		STATE:			MN
		ZIP:			55144-1000

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MINNESOTA MINING & MANUFACTURING CO
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-07-27</periodOfReport>

    <issuer>
        <issuerCik>0000066740</issuerCik>
        <issuerName>3M CO</issuerName>
        <issuerTradingSymbol>MMM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001304501</rptOwnerCik>
            <rptOwnerName>MacDonald Robert D III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3M CENTER</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55144-1000</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>VICE PRESIDENT MARKETING</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>Common Stock</value>
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                <value>E</value>
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                <value>Common Stock</value>
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            <transactionDate>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>17380</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>61.85</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
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            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>47335</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-07-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12384</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>86.80</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34951</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2010-07-27</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1825</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>86.80</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33126</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
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            </securityTitle>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
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        <nonDerivativeTransaction>
            <securityTitle>
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            <transactionDate>
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                <directOrIndirectOwnership>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <ownershipNature>
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                <natureOfOwnership>
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        </nonDerivativeHolding>
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            <expirationDate>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        <derivativeTransaction>
            <securityTitle>
                <value>Non-qualified Stock Option (Right to Buy)</value>
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            <conversionOrExercisePrice>
                <value>86.80</value>
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            <transactionDate>
                <value>2010-07-27</value>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>13067</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>86.80</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2011-01-27</value>
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            <expirationDate>
                <value>2012-05-14</value>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13067</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13067</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes shares acquired under 3M's General Employee Stock Purchase Plan.</footnote>
        <footnote id="F2">Includes shares acquired during the fiscal year pursuant to the 3M Voluntary Investment Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>George Ann Biros, attorney-in-fact for Robert D. MacDonald III</signatureName>
        <signatureDate>2010-07-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----