A soot discharge estimating device for an internal combustion engine comprising: steady discharge amount acquisition means configured to acquire a steady discharge amount of soot by using respective current values of the operation speed and the fuel injection amount with a previously stored relation between discharge amounts of soot discharged from the internal combustion engine and at least operation speeds and fuel injection amounts of the internal combustion engine where the internal combustion engine is in a steady operation state; steady value acquisition means configured to acquire a steady value of a mist equivalence ratio at a timing of starting ignition, wherein the mist equivalence ratio is the product of a ratio of a fuel amount to an air quantity in a fuel mist and a stoichiometric air fuel ratio, wherein the steady value acquisition means is configured to acquire the steady value by using respective current values of the operation speed and the fuel injection amount with a previously stored relation between values of operation speeds and fuel injection amounts that represent operation states of the internal combustion engine and the mist equivalence ratios at the timing of starting ignition where the internal combustion engine is in a steady operation state, and wherein the value of the mist equivalence ratio at the timing of starting ignition is obtained for an ignition delay period that is a period between a timing of starting fuel injection and the timing of starting ignition; transient value acquisition means configured to acquire a current value of the ignition delay period, and to acquire a transient value of the mist equivalence ratio at the timing of starting ignition using at least the acquired current value of the ignition delay period, wherein the transient value is a current value of the mist equivalence ratio at the timing of starting ignition; transient correction value calculation means configured to obtain the steady characteristic value from the steady value of the mist equivalence ratio at the timing of starting ignition and a previously stored characteristic relation, the characteristic relation representing changes in the discharge amount of soot values of the mist equivalence ratio, to obtain the transient characteristic value from the transient value of the mist equivalence ratio at the timing of starting ignition and the characteristic relation, and to calculate a transient correction value regarding the discharge amount of soot using a ratio of the steady characteristic value and a transient characteristic value; and soot discharge amount estimation means configured to estimate the discharge amount of soot by multiplying the steady discharge amount and the transient correction value. steady discharge amount acquisition means configured to acquire a steady discharge amount of soot by using respective current values of the operation speed and the fuel injection amount with a previously stored relation between discharge amounts of soot discharged from the internal combustion engine and at least operation speeds and fuel injection amounts of the internal combustion engine where the internal combustion engine is in a steady operation state; steady value acquisition means configured to acquire a steady value of a mist equivalence ratio at a timing of starting ignition, wherein the mist equivalence ratio is the product of a ratio of a fuel amount to an air quantity in a fuel mist and a stoichiometric air fuel ratio, wherein the steady value acquisition means is configured to acquire the steady value by using respective current values of the operation speed and the fuel injection amount with a previously stored relation between values of operation speeds and fuel injection amounts that represent operation states of the internal combustion engine and the mist equivalence ratios at the timing of starting ignition where the internal combustion engine is in a steady operation state, and wherein the value of the mist equivalence ratio at the timing of starting ignition is obtained for an ignition delay period that is a period between a timing of starting fuel injection and the timing of starting ignition; transient value acquisition means configured to acquire a current value of the ignition delay period, and to acquire a transient value of the mist equivalence ratio at the timing of starting ignition using at least the acquired current value of the ignition delay period, wherein the transient value is a current value of the mist equivalence ratio at the timing of starting ignition; transient correction value calculation means configured to obtain the steady characteristic value from the steady value of the mist equivalence ratio at the timing of starting ignition and a previously stored characteristic relation, the characteristic relation representing changes in the discharge amount of soot values of the mist equivalence ratio, to obtain the transient characteristic value from the transient value of the mist equivalence ratio at the timing of starting ignition and the characteristic relation, and to calculate a transient correction value regarding the discharge amount of soot using a ratio of the steady characteristic value and a transient characteristic value; and soot discharge amount estimation means configured to estimate the discharge amount of soot by multiplying the steady discharge amount and the transient correction value.