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

    <documentType>4</documentType><periodOfReport>2004-01-02</periodOfReport>
    <issuer>
        <issuerCik>0000105634</issuerCik>
        <issuerName>EMCOR GROUP INC</issuerName>
        <issuerTradingSymbol>EME</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001215543</rptOwnerCik>
            <rptOwnerName>MATZ R KEVIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>301 MERRITT SEVEN</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06851</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>SVP, Admin &amp; Strategic Service</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Options (right to buy)</value></securityTitle><conversionOrExercisePrice><value>43.83</value></conversionOrExercisePrice><transactionDate><value>2004-01-02</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>17970</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><value>2014-01-02</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>17970</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>17970</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">25% exercisable on 1/2/04; 25% exercisable on 1/2/05; 25% exercisable on 1/2/06; and 25% exercisable on 12/31/06.</footnote></footnotes><remarks/><ownerSignature><signatureName>R. Kevin Matz</signatureName><signatureDate>2004-01-05</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2004-01-02
0000105634
EMCOR GROUP INC
EME
0001215543
MATZ R KEVIN
301 MERRITT SEVEN
NORWALK
CT
06851
0
1
0
0
SVP, Admin & Strategic Service
Employee Stock Options (right to buy)
43.83
2004-01-02
4
A
0
17970
0
A
2014-01-02
Common Stock
17970
17970
D
25% exercisable on 1/2/04; 25% exercisable on 1/2/05; 25% exercisable on 1/2/06; and 25% exercisable on 12/31/06.
R. Kevin Matz
2004-01-05