<SUBMISSION>
<ACCESSION-NUMBER>0001181474-04-000028
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20041230
<FILING-DATE>20041230
<DATE-OF-FILING-DATE-CHANGE>20041230
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CADENCE DESIGN SYSTEMS INC
<CIK>0000813672
<ASSIGNED-SIC>7372
<IRS-NUMBER>770148231
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0102
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>2655 SEELY ROAD BLDG 5
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
<PHONE>4089431234
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>555 RIVER OAKS PARKWAY
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>ECAD INC /DE/
<DATE-CHANGED>19880609
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>PORTER WILLIAM
<CIK>0001181479
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-10606
<FILM-NUMBER>041233124
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>2655 SEALY AVE.
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
<PHONE>4089431234
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O CADENCE DESIGN SYSTEN INC
<STREET2>2655 SEELY RD
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-12-30</periodOfReport>

    <issuer>
        <issuerCik>0000813672</issuerCik>
        <issuerName>CADENCE DESIGN SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CDN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001181479</rptOwnerCik>
            <rptOwnerName>PORTER WILLIAM</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2655 SEELY AVENUE, BLDG. 5</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95134</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-12-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>150000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>191545</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Issuance of restricted stock.</footnote>
        <footnote id="F2">Includes 2,520 shares acquired through the Cadence Design Systems, Inc. Employee Stock Purchase Plan on January 31, 2003 and 2,551 shares acquired through the Cadence Design Systems, Inc. Employee Stock Purchase Plan on January 30, 2004.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>William Porter</signatureName>
        <signatureDate>2004-12-30</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
