-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 MxuZBMQXsgdYHkl9Wc4AgYquCVL+GE8lSa4wKKq8YCjmQrHKSJ9hwEYn/6KabIUK
 uJdDUhZax6jQlRtG8v8MXA==

<SEC-DOCUMENT>0001109546-09-000009.txt : 20090527
<SEC-HEADER>0001109546-09-000009.hdr.sgml : 20090527
<ACCEPTANCE-DATETIME>20090527174024
ACCESSION NUMBER:		0001109546-09-000009
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090527
FILED AS OF DATE:		20090527
DATE AS OF CHANGE:		20090527

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Williams Gary Michael
		CENTRAL INDEX KEY:			0001410284

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30777
		FILM NUMBER:		09855514

	MAIL ADDRESS:	
		STREET 1:		949 SOUTH COAST DRIVE
		STREET 2:		THIRD FLOOR
		CITY:			COSTA MESA
		STATE:			CA
		ZIP:			92626

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PACIFIC MERCANTILE BANCORP
		CENTRAL INDEX KEY:			0001109546
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		IRS NUMBER:				330898238
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		949 SOUTH COAST DRIVE
		STREET 2:		THIRD FLOOR
		CITY:			COSTA MESA
		STATE:			CA
		ZIP:			92626
		BUSINESS PHONE:		714-438-2500

	MAIL ADDRESS:	
		STREET 1:		949 SOUTH COAST DRIVE
		STREET 2:		THIRD FLOOR
		CITY:			COSTA MESA
		STATE:			CA
		ZIP:			92626
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-05-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001109546</issuerCik>
        <issuerName>PACIFIC MERCANTILE BANCORP</issuerName>
        <issuerTradingSymbol>PMBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001410284</rptOwnerCik>
            <rptOwnerName>Williams Gary Michael</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>949 SOUTH COAST DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>THIRD FLOOR</rptOwnerStreet2>
            <rptOwnerCity>COSTA MESA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92626</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-05-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78906</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-05-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>551</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>79457</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Barbara Palermo</signatureName>
        <signatureDate>2009-05-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----