To determine abnormality of an EGR route based on behavior of an ion current, and to achieve control action responding thereto.

The combustion control device for the internal combustion engine includes a switching element Q controlling energization of an ignition coil CL; a control device ECU performing ON/OFF action of the switching element and performing EGR control at an appropriate timing; an ignition plug PG receiving an induced voltage of the ignition coil CL and performing ignition discharge; and a signal detection circuit ION detecting a current signal Vo of the ignition plug PG after the ignition discharge and feeding it to the control device ECU. Determination means (ST2-ST7) specifying an LC vibration wave generated after the ignition discharge based on the current signal Vo and determining the abnormality of the EGR route based on the fact whether or not the converging timing of the LC vibration wave is more quick than the regular timing in the operation state; and a changing means (ST8) changing the combustion control content after that when the abnormality of the EGR route is determined are provided.

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