<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-01-05</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000097216</issuerCik>
        <issuerName>TEREX CORP</issuerName>
        <issuerTradingSymbol>TEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001196974</rptOwnerCik>
            <rptOwnerName>WEHMEIER HELGE H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BAYER CORP</rptOwnerStreet1>
            <rptOwnerStreet2>HILLSIDE DRIVE BLACKBURN RD</rptOwnerStreet2>
            <rptOwnerCity>SEWICKLEY</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>15143</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, par value $.01</value>
            </securityTitle>
            <transactionDate>
                <value>2004-01-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2160</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.93</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21193</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.01</value>
            </securityTitle>
            <transactionDate>
                <value>2004-01-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>216</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.93</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21409</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares purchased through company deferred compensation plan representing annual director retainer.</footnote>
        <footnote id="F2">Represent shares beneficially owned as of January 5, 2004.</footnote>
        <footnote id="F3">Shares purchased through company deferred compensation plan representing annual committee retainer.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>/s/  HELGE H. WEHMEIER</signatureName>
        <signatureDate>2004-01-06</signatureDate>
    </ownerSignature>

</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "primary_doc.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 5023}]
X0201
4
2004-01-05
0
0000097216
TEREX CORP
TEX
0001196974
WEHMEIER HELGE H
BAYER CORP
HILLSIDE DRIVE BLACKBURN RD
SEWICKLEY
PA
15143
1
0
0
0
Common Stock, par value $.01
2004-01-05
4
P
0
2160
28.93
A
21193
D
Common Stock, par value $.01
2004-01-05
4
P
0
216
28.93
A
21409
D
Shares purchased through company deferred compensation plan representing annual director retainer.
Represent shares beneficially owned as of January 5, 2004.
Shares purchased through company deferred compensation plan representing annual committee retainer.
/s/  HELGE H. WEHMEIER
2004-01-06