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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2018-10-01</periodOfReport>

    <dateOfOriginalSubmission>2018-10-03</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000026076</issuerCik>
        <issuerName>CUBIC CORP /DE/</issuerName>
        <issuerTradingSymbol>CUB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001755059</rptOwnerCik>
            <rptOwnerName>KNOWLES MICHAEL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>9333 BALBOA AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92123</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, CMPS - SVP, CORP</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>896</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Form 3 filed on October 3, 2018 inadvertently omitted these restricted stock units.</footnote>
        <footnote id="F2">The performance-based RSUs vest on the date the Board of Directors certifies CUB's sales growth, EBITDA growth, and return on equity for the three-year performance period ending on September 30, 2020, subject to the Reporting Person's continued service with CUB through such vesting date, except as otherwise provided in the applicable RSU agreement. The RSUs vest based 40% on sales growth, 40% on EBITDA growth, and 20% on the return on equity achieved by CUB during such performance period. Dividend equivalent rights accrue with respect to the RSUs when and as dividends are paid on CUB common stock and vest proportionately with the RSUs to which they relate. Vested shares and accrued dividends will be delivered to the Reporting Person following the vesting date.</footnote>
        <footnote id="F3">Each RSU represents a contingent right to receive one share of CUB common stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Hilary L. Hageman, Attorney-in-fact for Michael Knowles</signatureName>
        <signatureDate>2020-10-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
