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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,
 Lt0v8paWWsIKljc12WM1qFqHUebupUxZEJgZVb+zIwkX2lWLGEZe+lL7lzrERqY3
 osYFCOyl7xdaboAeMbD2tw==

<SEC-DOCUMENT>0001289895-08-000062.txt : 20081104
<SEC-HEADER>0001289895-08-000062.hdr.sgml : 20081104
<ACCEPTANCE-DATETIME>20081104155944
ACCESSION NUMBER:		0001289895-08-000062
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081027
FILED AS OF DATE:		20081104
DATE AS OF CHANGE:		20081104

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AIRGAS INC
		CENTRAL INDEX KEY:			0000804212
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-INDUSTRIAL MACHINERY & EQUIPMENT [5084]
		IRS NUMBER:				560732648
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		259 N. RADNOR-CHESTER ROAD
		STREET 2:		SUITE 100
		CITY:			RADNOR
		STATE:			PA
		ZIP:			19087
		BUSINESS PHONE:		6106875253

	MAIL ADDRESS:	
		STREET 1:		259 N. RADNOR-CHESTER ROAD
		STREET 2:		SUITE 100
		CITY:			RADNOR
		STATE:			PA
		ZIP:			19087

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SNEED PAULA A
		CENTRAL INDEX KEY:			0001193024

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09344
		FILM NUMBER:		081160946

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		8476466687

	MAIL ADDRESS:	
		STREET 1:		THREE LAKES DRIVE
		CITY:			NORTHFIELD
		STATE:			IL
		ZIP:			60093
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2008-10-27</periodOfReport>

    <dateOfOriginalSubmission>2008-10-29</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000804212</issuerCik>
        <issuerName>AIRGAS INC</issuerName>
        <issuerTradingSymbol>ARG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001193024</rptOwnerCik>
            <rptOwnerName>SNEED PAULA A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AIRGAS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>259 N. RADNOR-CHESTER ROAD, STE. 100</rptOwnerStreet2>
            <rptOwnerCity>RADNOR</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19087</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-10-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>23756</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares were originally reported on a Form 4 filed on October 29, 2008 as having been sold by the reporting person on the same date.  The previously reported sale transaction was broken and unwound by the reporting person's broker through the broker's error account and, therefore, did not, in fact, occur for the reporting person's account.  As of October 29, 2008, the reporting person beneficially owned 23,756 shares of common stock of Airgas, Inc.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Robert H. Young, Jr., Attorney-in-Fact for Paula A. Sneed</signatureName>
        <signatureDate>2008-11-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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