-----BEGIN PRIVACY-ENHANCED MESSAGE-----
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,
 TfGE/qTh4LfD+0WJvtcOi5rKgJzZpdIY86Jmm2/eUD0CrLSGFppsi/iR81e51dcL
 +9HnSib8zEPB95ezMpvbgA==

<SEC-DOCUMENT>0001289895-08-000014.txt : 20080522
<SEC-HEADER>0001289895-08-000014.hdr.sgml : 20080522
<ACCEPTANCE-DATETIME>20080522115437
ACCESSION NUMBER:		0001289895-08-000014
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080520
FILED AS OF DATE:		20080522
DATE AS OF CHANGE:		20080522

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:			Graff Leslie J
		CENTRAL INDEX KEY:			0001373454

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09344
		FILM NUMBER:		08853816

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		610-687-5253

	MAIL ADDRESS:	
		STREET 1:		259 N. RADNOR-CHESTER RD.
		CITY:			RADNOR
		STATE:			PA
		ZIP:			19087
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-20</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001373454</rptOwnerCik>
            <rptOwnerName>Graff Leslie J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AIRGAS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>259 N. RADNOR-CHESTER ROAD, SUITE 100</rptOwnerStreet2>
            <rptOwnerCity>RADNOR</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19087</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP Corporate Development</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>60.84</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-05-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-05-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>14700</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14700</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These options became exercisable in 25% equal increments on each of 5/20/2009, 5/20/2010, 5/20/2011 and 5/20/2012.</footnote>
        <footnote id="F2">Not Applicable.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Robert H. Young, Jr., Attorney-In-Fact for Leslie J. Graff</signatureName>
        <signatureDate>2008-05-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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