A glow plug is provided in a combustion chamber of a diesel engine. An ECU diagnoses existence or nonexistence of a disconnection abnormality of the glow plug through a controller. When there is an abnormality in the glow plug, processing for cutting fuel supply of an abnormal cylinder, processing for increasing fuel injection quantity of a normal cylinder, processing for delaying injection timing of the abnormal cylinder, or processing for delaying valve timing of an intake valve of the abnormal cylinder is performed. Thus, suitable startability of the engine can be ensured even when the abnormality occurs in the glow plug.