-----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,
 Mh2j/ZHJAwJBPKLYu+bq2WV2I8kCAMEjp+r+Fd6UoLKQNs+ThcsJhdiUB/0qxZ7F
 uY5eSc6KJ6UNBf+ExwyfYA==

<SEC-DOCUMENT>0001209191-05-035065.txt : 20050705
<SEC-HEADER>0001209191-05-035065.hdr.sgml : 20050704
<ACCEPTANCE-DATETIME>20050705153459
ACCESSION NUMBER:		0001209191-05-035065
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050701
FILED AS OF DATE:		20050705
DATE AS OF CHANGE:		20050705

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FRANK FRANCES H
		CENTRAL INDEX KEY:			0001223979

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-32561
		FILM NUMBER:		05936822

	BUSINESS ADDRESS:	
		STREET 1:		15985 EAST HIGH STREET
		STREET 2:		P.O. BOX 35
		CITY:			MIDDLEFIELD
		STATE:			OH
		ZIP:			44062-9263

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MIDDLEFIELD BANC CORP
		CENTRAL INDEX KEY:			0000836147
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				341585111
		STATE OF INCORPORATION:			OH

	BUSINESS ADDRESS:	
		STREET 1:		15985 E HIGH ST
		STREET 2:		P O BOX 35
		CITY:			MIDDLEFILED
		STATE:			OH
		ZIP:			44062-9263
		BUSINESS PHONE:		4406321666

	MAIL ADDRESS:	
		STREET 1:		15985 EAST HIGH STREET
		STREET 2:		P O BOX 35
		CITY:			MIDDLEFIELD
		STATE:			OH
		ZIP:			44062-9263
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-07-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000836147</issuerCik>
        <issuerName>MIDDLEFIELD BANC CORP</issuerName>
        <issuerTradingSymbol>MBCN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001223979</rptOwnerCik>
            <rptOwnerName>FRANK FRANCES H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>15985 EAST HIGH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>P. O. BOX 35</rptOwnerStreet2>
            <rptOwnerCity>MIDDLEFIELD</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44062</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>2005-07-01</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2005-07-01</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>41.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4665.797</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3236.886</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes shares acquired under the MBCN Dividend Reinvestment Plan.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>James R. Heslop, 2nd
Power of Attorney for
Frances H. Frank</signatureName>
        <signatureDate>2005-07-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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