<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-11-19</periodOfReport>
    <issuer>
        <issuerCik>0000009984</issuerCik>
        <issuerName>BARNES GROUP INC</issuerName>
        <issuerTradingSymbol>B</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001195682</rptOwnerCik>
            <rptOwnerName>CARPENTER EDMUND M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BARNES GROUP INC.</rptOwnerStreet1>
            <rptOwnerStreet2>123 MAIN STREET</rptOwnerStreet2>
            <rptOwnerCity>BRISTOL</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06011-0489</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
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Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5068.7695</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Employee Stk Purchase Plan</value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4330.941</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By 401(k) Plan</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>20.10</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>31499</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2002-08-15</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2010-02-10</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>31499</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>28.58</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>25093</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-11-19</value></exerciseDate><expirationDate><value>2010-02-10</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>25093</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>25093</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>20.10</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>26858</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2002-08-15</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2009-02-19</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>26858</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>28.58</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>21396</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-11-19</value></exerciseDate><expirationDate><value>2009-02-19</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>21396</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>21396</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>20.20</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5966</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2001-11-12</value><footnoteId id="F3"/></exerciseDate><expirationDate><value>2010-02-10</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5966</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>24310</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Employee Stk Option-Right to Buy</value></securityTitle><conversionOrExercisePrice><value>28.58</value></conversionOrExercisePrice><transactionDate><value>2003-11-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>4768</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-11-19</value></exerciseDate><expirationDate><value>2010-02-10</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>4768</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4768</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Includes 45,000 Restricted Stock Units and 45,000 Performance-Based Restricted Stock Units that are subject to forfeiture if certain events occur.</footnote><footnote id="F2">The options vest 100% immediately on 8/15/2002.</footnote><footnote id="F3">The options vest 100% immediately on 11/12/2001.</footnote><footnote id="F4">Security converts to common stock on a one for one basis.</footnote></footnotes><remarks/><ownerSignature><signatureName>Nancy M. Clark, pursuant to a Power of Atty</signatureName><signatureDate>2003-11-20</signatureDate></ownerSignature></ownershipDocument>

