Internal Combustion Engine Control Device

An internal combustion engine control device includes: a rotation speed calculating unit that calculates crank rotation speeds of an engine; an extreme timing calculating unit that calculates an extreme timing of the crank rotation speeds; and an average rotation speed calculating unit that calculates an average rotation speed of the crank rotation speeds; and a combustion state estimating unit that estimates a combustion state in the engine based on the extreme timing and the average rotation speed.