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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0000067472-05-000035.txt : 20050426
<SEC-HEADER>0000067472-05-000035.hdr.sgml : 20050426
<ACCEPTANCE-DATETIME>20050426135833
ACCESSION NUMBER:		0000067472-05-000035
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050425
FILED AS OF DATE:		20050426
DATE AS OF CHANGE:		20050426

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MOLEX INC
		CENTRAL INDEX KEY:			0000067472
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRONIC CONNECTORS [3678]
		IRS NUMBER:				362369491
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		2222 WELLINGTON CT
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532
		BUSINESS PHONE:		6309694550

	MAIL ADDRESS:	
		STREET 1:		2222 WELLINGTON COURT
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LAYMON JOE W
		CENTRAL INDEX KEY:			0001190844

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-07491
		FILM NUMBER:		05772390

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		313 322 3000

	MAIL ADDRESS:	
		STREET 1:		FORD MOTOR COMPANY
		STREET 2:		ONE AMERICAN RD
		CITY:			DEARBORN
		STATE:			MI
		ZIP:			48126
</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>2005-04-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000067472</issuerCik>
        <issuerName>MOLEX INC</issuerName>
        <issuerTradingSymbol>MOLX MOLXA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190844</rptOwnerCik>
            <rptOwnerName>LAYMON JOE W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>FORD MOTOR COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>ONE AMERICAN RD</rptOwnerStreet2>
            <rptOwnerCity>DEARBORN</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48126</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-04-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>680.517</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>24.78</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-04-25</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-04-25</value>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>680.517</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3024.072</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The phantom stock units were accrued quarterly on the first business day following the 24th of January, April, July and October under The Molex Incorporated Deferred Compensation Plan and are to be settled 100% in cash upon the reporting person's termination from service on the Issuer's Board of Directors.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Joe W. Laymon</signatureName>
        <signatureDate>2005-04-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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