<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-05-21</periodOfReport>
    <issuer>
        <issuerCik>0000072331</issuerCik>
        <issuerName>NORDSON CORP</issuerName>
        <issuerTradingSymbol>NDSN</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001018621</rptOwnerCik>
            <rptOwnerName>BROWN GLENN R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Stock Units</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F1"/></conversionOrExercisePrice><transactionDate><value>2003-05-21</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>121</value></transactionShares><transactionValue><value>0</value><footnoteId id="F2"/></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value></exerciseDate><expirationDate><value>1988-08-08</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>COMMON SHARES</value></underlyingSecurityTitle><underlyingSecurityShares><value>121</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>25398</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">Security converts common stock on one-for-one basis.</footnote><footnote id="F2">Stock units accrued through Nordson's Directors' Deferred Compensation Plan as of 5/21/03.  Receipt of stock is not permissible until the Director ceases to be a Director.</footnote></footnotes><ownerSignature><signatureName>Robert E. Veillette, Attorney-In-Fact</signatureName><signatureDate>2003-05-23</signatureDate></ownerSignature></ownershipDocument>

