    <SEC-DOCUMENT>0000815556-22-000011-index.html : 20220210
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    <ACCEPTANCE-DATETIME>20220210172243
    ACCESSION NUMBER:		0000815556-22-000011
    CONFORMED SUBMISSION TYPE:	10-K/A
    PUBLIC DOCUMENT COUNT:		29
    CONFORMED PERIOD OF REPORT:	20211231
    FILED AS OF DATE:		20220210
    DATE AS OF CHANGE:		20220210

    FILER:

    	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

    	FILING VALUES:
    		FORM TYPE:		10-K/A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-16125
    		FILM NUMBER:		22615386

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

    	MAIL ADDRESS:
    		STREET 1:		2001 THEURER BLVD
    		CITY:			WINONA
    		STATE:			MN
    		ZIP:			55987
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>10-K/A
    <SEQUENCE>1
    <FILENAME>fast-20211231.htm
    <DESCRIPTION>10-K/A
    <TEXT>
    Document 1 - file: fast-20211231.htm

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    <DOCUMENT>
    <TYPE>EX-10.4
    <SEQUENCE>2
    <FILENAME>fast1231202110-kaexhibit104.htm
    <DESCRIPTION>FASTENAL COMPANY NON-EMPLOYEE DIRECTOR STOCK OPTION PLAN
    <TEXT>
    Document 2 - file: fast1231202110-kaexhibit104.htm

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    <TYPE>EX-31.3
    <SEQUENCE>3
    <FILENAME>fast1231202110-kaexhibit313.htm
    <DESCRIPTION>CERTIFICATION OF CEO UNDER SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 3 - file: fast1231202110-kaexhibit313.htm

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    <TYPE>EX-31.4
    <SEQUENCE>4
    <FILENAME>fast1231202110-kaexhibit314.htm
    <DESCRIPTION>CERTIFICATION OF CFO UNDER SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
    <TEXT>
    Document 4 - file: fast1231202110-kaexhibit314.htm

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    <TYPE>EX-99.1
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    <FILENAME>glossywrap-printversion.htm
    <DESCRIPTION>2021 ANNUAL REPORT TO SHAREHOLDERS
    <TEXT>
    Document 5 - file: glossywrap-printversion.htm

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    <SEQUENCE>6
    <FILENAME>glossywrap-printversion001.jpg
    <DESCRIPTION>GRAPHIC
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    Document 12 - file: glossywrap-printversion007.jpg

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    Document 13 - file: glossywrap-printversion008.jpg

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    <TYPE>EX-101.SCH
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    <FILENAME>fast-20211231.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 18 - file: fast-20211231.xsd

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    <FILENAME>fast-20211231_lab.xml
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    Document 19 - file: fast-20211231_lab.xml

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    <TEXT>
    Document 24 - file: Financial_Report.xlsx

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    <SEQUENCE>25
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    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 25 - file: Show.js

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    <TYPE>XML
    <SEQUENCE>26
    <FILENAME>report.css
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    <TEXT>
    Document 26 - file: report.css

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    <SEQUENCE>27
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    <TEXT>
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    <SEQUENCE>30
    <FILENAME>MetaLinks.json
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    <TEXT>
    Document 30 - file: MetaLinks.json

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