A fourth cylinder is mounted with a cylinder pressure sensor. The injection timing of the fourth cylinder is operated so as to feedback control the ignition timing of the fourth cylinder, which is detected by the cylinder pressure sensor, to a target ignition timing. The ignition timings of the first cylinder to the third cylinder are indirectly controlled by operating the injection timings so as to make output torques produced by combustion in the first cylinder to the third cylinder correspond to an output torque produced by combustion in the fourth cylinder.