<SEC-DOCUMENT>0001179110-13-002530.txt : 20130212
<SEC-HEADER>0001179110-13-002530.hdr.sgml : 20130212
<ACCEPTANCE-DATETIME>20130212180315
ACCESSION NUMBER:		0001179110-13-002530
CONFORMED SUBMISSION TYPE:	5/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20121231
FILED AS OF DATE:		20130212
DATE AS OF CHANGE:		20130212

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FASTENAL CO
		CENTRAL INDEX KEY:			0000815556
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-BUILDING MATERIALS, HARDWARE, GARDEN SUPPLY [5200]
		IRS NUMBER:				410948415
		STATE OF INCORPORATION:			MN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2001 THEURER BLVD
		CITY:			WINONA
		STATE:			MN
		ZIP:			55987
		BUSINESS PHONE:		5074545374

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Ancius Michael J
		CENTRAL INDEX KEY:			0001454708

	FILING VALUES:
		FORM TYPE:		5/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-16125
		FILM NUMBER:		13598707

	MAIL ADDRESS:	
		STREET 1:		151 COACHLITE COURT NORTH
		CITY:			ONALASKA
		STATE:			WI
		ZIP:			54650
</SEC-HEADER>
<DOCUMENT>
<TYPE>5/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 5/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>5/A</documentType>

    <periodOfReport>2012-12-31</periodOfReport>

    <dateOfOriginalSubmission>2013-02-01</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000815556</issuerCik>
        <issuerName>FASTENAL CO</issuerName>
        <issuerTradingSymbol>FAST</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001454708</rptOwnerCik>
            <rptOwnerName>Ancius Michael J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>151 COACHLITE COURT</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ONALASKA</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>54650</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-08-24</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>L</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>44.265</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>211</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held in child custodian account</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Form 5 filed on 2/1/2013 provided the incorrect date of 8/24/2013.</footnote>
        <footnote id="F2">Amount was correctly stated in the 2/1/2013 Form 5 filing, but is restated to gain access to the reporting system.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John J. Milek, Attorney-in-Fact</signatureName>
        <signatureDate>2013-02-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
