<SEC-DOCUMENT>0001209191-18-047768.txt : 20180821
<SEC-HEADER>0001209191-18-047768.hdr.sgml : 20180821
<ACCEPTANCE-DATETIME>20180821170007
ACCESSION NUMBER:		0001209191-18-047768
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180817
FILED AS OF DATE:		20180821
DATE AS OF CHANGE:		20180821

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Graham Todd A
		CENTRAL INDEX KEY:			0001429604

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38084
		FILM NUMBER:		181030813

	MAIL ADDRESS:	
		STREET 1:		4083 AUTUMN VIEW CT
		CITY:			FENTON
		STATE:			MI
		ZIP:			48430

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FARMERS & MERCHANTS BANCORP INC
		CENTRAL INDEX KEY:			0000792966
		STANDARD INDUSTRIAL CLASSIFICATION:	SAVINGS INSTITUTION, FEDERALLY CHARTERED [6035]
		IRS NUMBER:				341469491
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		307-11 N DEFIANCE ST
		CITY:			ARCHBOLD
		STATE:			OH
		ZIP:			43502
		BUSINESS PHONE:		4194462501

	MAIL ADDRESS:	
		STREET 1:		307-11 NORTH DEFIANCE ST
		CITY:			ARCHBOLD
		STATE:			OH
		ZIP:			43502
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-08-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000792966</issuerCik>
        <issuerName>FARMERS &amp; MERCHANTS BANCORP INC</issuerName>
        <issuerTradingSymbol>FMAO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001429604</rptOwnerCik>
            <rptOwnerName>Graham Todd A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>240 WESTFIELD DR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ARCHBOLD</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>43502</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice Pres</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON</value>
            </securityTitle>
            <transactionDate>
                <value>2018-08-17</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3703</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Stock acquired as a result of stock awards issued pursuant to the Company's Long Term Incentive Plan</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Todd A Graham</signatureName>
        <signatureDate>2018-08-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
