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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2022-06-03</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001013488</issuerCik>
        <issuerName>BJs RESTAURANTS INC</issuerName>
        <issuerTradingSymbol>BJRI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001512516</rptOwnerCik>
            <rptOwnerName>Pinsak Christopher P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7755 CENTER AVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>HUNTINGTON BEACH</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92647</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7164</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>53.22</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2020-01-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2029-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3711</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>38.90</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2021-01-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3714</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>46.91</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2022-01-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2031-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3504</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>32.27</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2023-01-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2032-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3836</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Amount includes 3,750 of unvested Restricted Stock Units, 500 vesting in one installment on January 15, 2023, 1,184 vesting in two installments beginning on January 15, 2023, and 2,066 vesting in three installments beginning on January 15, 2023.</footnote>
        <footnote id="F2">Amount includes 1,857 vested options and 1,857 vesting on January 15, 2023.</footnote>
        <footnote id="F3">Amount includes 1,168 vested options and 2,336 vesting in two equal annual installments beginning on January 15, 2023.</footnote>
        <footnote id="F4">These stock options begin vesting 33.3% per year beginning on January 15, 2023.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jacob J. Guild, Attorney-in-Fact for Christopher P. Pinsak</signatureName>
        <signatureDate>2022-11-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
