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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-04-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000715446</issuerCik>
        <issuerName>Anixa Biosciences Inc</issuerName>
        <issuerTradingSymbol>ANIX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001689394</rptOwnerCik>
            <rptOwnerName>Catelani Michael</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ANIXA BIOSCIENCES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3150 ALMADEN EXPRESSWAY, SUITE 250</rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95118</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>COO &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1867</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.61</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5829</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person purchased the shares of common stock reported hereunder pursuant to the Anixa Biosciences, Inc. Employee Stock Purchase Plan (the Plan) which satisfies the requirements of Section 423 of the Internal Revenue Code.  The reporting persons purchase of the shares of common stock is exempt from Section 16(b) under Rule 16b-3(c) and is exempt from the reporting requirements of Section 16 by virtue of Rule 16a-3(f)(1)(i)(B), however the reporting person has elected to voluntarily report the acquisition of the shares.</footnote>
        <footnote id="F2">In accordance with the Plan, the shares were purchased based on 85% of the closing price of Anixa Biosciences, Inc. common stock on April 30, 2020.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michael J. Catelani</signatureName>
        <signatureDate>2020-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
