<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType><periodOfReport>2004-01-06</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001008554</issuerCik>
        <issuerName>HUMBOLDT BANCORP</issuerName>
        <issuerTradingSymbol>HBEK</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001250402</rptOwnerCik>
            <rptOwnerName>MONTNA AL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HUMBOLDT BANCORP</rptOwnerStreet1>
            <rptOwnerStreet2>2998 DOUGLAS BLVD., STE 330</rptOwnerStreet2>
            <rptOwnerCity>ROSEVILLE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95661</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Common Stock </value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1737</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>by Charles Schwab IRA </value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock </value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2894</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>by Charles Schwab - Montna Farms Dryer</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Stock Option Right to Buy</value></securityTitle><conversionOrExercisePrice><value>7.87</value><footnoteId id="F2"/></conversionOrExercisePrice><exerciseDate><value>1999-04-13</value></exerciseDate><expirationDate><value>2009-04-12</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stocl </value></underlyingSecurityTitle><underlyingSecurityShares><value>14148</value><footnoteId id="F2"/></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Option Right to Buy</value></securityTitle><conversionOrExercisePrice><value>8.57</value><footnoteId id="F2"/></conversionOrExercisePrice><exerciseDate><value>2000-09-19</value></exerciseDate><expirationDate><value>2010-09-19</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock </value></underlyingSecurityTitle><underlyingSecurityShares><value>1997</value><footnoteId id="F2"/></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Option Right to Buy</value></securityTitle><conversionOrExercisePrice><value>8.60</value><footnoteId id="F2"/></conversionOrExercisePrice><exerciseDate><value>2002-09-18</value></exerciseDate><expirationDate><value>2012-09-17</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock </value></underlyingSecurityTitle><underlyingSecurityShares><value>12041</value><footnoteId id="F2"/></underlyingSecurityShares></underlyingSecurity><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes><footnote id="F1"> Represents the number of shares of California Independent Bancorp prior
to the merger between Humboldt Bancorp and California Independent Bancorp.
Under the terms of the merger agreement, each share of California
Independent Bancorp common stock shall be converted into the right to
receive, at the election of each shareholder of California Independent
Bancorp, and subject to proration, either (i)2.1965 shares of Humboldt
Bancorp common stock or (ii) $38.79 in cash.  Upon the completion of the
allocation procedure and final results by Illinois Stock transfer, the
Exchange Agent, this Form will be amended to reflect the final amounts.</footnote><footnote id="F2">The number of shares of Humboldt Bancorp common stock subject to options
and corresponding exercise price has been adjusted to reflect the conversion
ratio of 2.1965 shares of Humboldt Bancorp common stock for each share of
California Independent Bancorp common stock.</footnote></footnotes><remarks/><ownerSignature><signatureName>Alfred G. Montna</signatureName><signatureDate>2004-01-12</signatureDate></ownerSignature><ownerSignature><signatureName>Signed by Patrick J. Rusnak, Power of Attorney on File</signatureName><signatureDate>2004-01-12</signatureDate></ownerSignature></ownershipDocument>

