<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-02-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001084580</issuerCik>
        <issuerName>JEFFERIES GROUP INC /DE/</issuerName>
        <issuerTradingSymbol>JEF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001275002</rptOwnerCik>
            <rptOwnerName>FRIEDMAN BRIAN P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman, Executive Committee</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-02-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>19414</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>54.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1471485</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Does not include 578 shares indirectly held by the Reporting Person by the Trustee of the Jefferies Group, Inc. Employees' Stock Ownership Plan for the benefit of the Reporting Person, and does not include 2,835 shares indirectly held by the Reporting Person by the Trustee under the Jefferies Group, Inc. Profit Sharing Plan for the benefit of the Reporting Person.  Includes up to 520,000 shares that may be issued to the Reporting Person pursuant to an agreement with Jefferies Group, Inc. to issue up to such amount of shares upon the receipt by Jefferies Capital Partners IV L.P., a private equity fund, of threshold levels of committed capital at the final closing of the fund, subject to clawback based upon the size of a subsequent fund and subject to certain other conditions. This issuance is expected to occur eighteen months after the final closing of the fund or such earlier date as determined by the Reporting Person.</footnote>
        <footnote id="F2">Acquisition of restricted stock units under the Jefferies Group, Inc. 2003 Incentive Compensation Plan in lieu of cash compensation in a transaction exempt under Rule 16b-3(d) under the Securities Exchange Act of 1934. The restricted stock units vest 20% on each of February 1, 2007. February 1, 2008, February 1, 2009, February 1, 2010 and December 15, 2010.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Roland T. Kelly, by power of attorney</signatureName>
        <signatureDate>2006-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
