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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-01-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001025877</issuerCik>
        <issuerName>DCB FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>dcbf.ob</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252354</rptOwnerCik>
            <rptOwnerName>STEVENSON ADAM</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>DCB Financial Corp Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-01-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>443</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.2</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16733</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>23.4</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-06-23</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-06-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>213</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.4</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-06-13</value>
                <footnoteId id="F1"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-06-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>196</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>30.7</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-06-21</value>
                <footnoteId id="F1"/>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-06-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>326</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>23</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2008-06-20</value>
                <footnoteId id="F1"/>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-06-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>435</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.9</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2009-02-20</value>
                <footnoteId id="F1"/>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-02-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>592</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2010-06-17</value>
                <footnoteId id="F1"/>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-06-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>556</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.5</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2011-12-21</value>
                <footnoteId id="F1"/>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-12-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1429</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>DCBF Employee Stock Options-Calls</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.5</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2013-12-21</value>
                <footnoteId id="F1"/>
                <footnoteId id="F9"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-12-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>DCB Financial Corp Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1111</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The options vest in five equal annual installments beginning one year after the grant date and expire ten years after the grant date.</footnote>
        <footnote id="F2">Options granted 6/23/2004.</footnote>
        <footnote id="F3">Options granted 6/13/2005.</footnote>
        <footnote id="F4">Options granted 6/21/2006.</footnote>
        <footnote id="F5">Options granted 6/20/2007.</footnote>
        <footnote id="F6">Options granted 2/20/2008.</footnote>
        <footnote id="F7">Options granted 6/17/2009.</footnote>
        <footnote id="F8">Options granted 12/21/2010.</footnote>
        <footnote id="F9">Options granted 12/21/2012.</footnote>
    </footnotes>

    <remarks>The Option grants were previously reported in aggregate.</remarks>

    <ownerSignature>
        <signatureName>Adam Stevenson, by Charles M. Diersing, Attorney in Fact</signatureName>
        <signatureDate>2014-01-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
