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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,
 J8dWGKx/coAT/aXnXk+3h0N0tUDO3W+XHNm0gY08dcW4iHfsJE1yJfKOtKJhYxFL
 MBq6rE4zYvJDCHmwfvHE0w==

<SEC-DOCUMENT>0001179110-06-004844.txt : 20060227
<SEC-HEADER>0001179110-06-004844.hdr.sgml : 20060227
<ACCEPTANCE-DATETIME>20060227112632
ACCESSION NUMBER:		0001179110-06-004844
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060224
FILED AS OF DATE:		20060227
DATE AS OF CHANGE:		20060227

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:			SLAGGIE STEPHEN M
		CENTRAL INDEX KEY:			0000901069

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-16125
		FILM NUMBER:		06645369

	BUSINESS ADDRESS:	
		STREET 1:		FASTENAL CO
		STREET 2:		2001 THEURER BLVD P O BOX 978
		CITY:			WINONA
		STATE:			MN
		ZIP:			55987
		BUSINESS PHONE:		507-454-5374

	MAIL ADDRESS:	
		STREET 1:		FASTENAL CO 2001 THEURER BLVD
		STREET 2:		P O BOX 978
		CITY:			WINONA
		STATE:			MN
		ZIP:			55987
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-02-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000901069</rptOwnerCik>
            <rptOwnerName>SLAGGIE STEPHEN M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2001THEURER BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WINONA</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55987</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>2006-02-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11508</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>43.33</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6203374</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">An additional 144300 shares of issuers common stock are held by the reporting person and the reporting persons child as custodian for the reporting persons child. An additional 419660 shares of issuers common stock are held by the reporting persons spouse. The reporting person disclaims beneficial ownership of the shares listed in this footnote.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John Milek, Attorney-in-Fact</signatureName>
        <signatureDate>2006-02-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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