An internal combustion engine provided with a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to control a closing timing of an intake valve. An actual compression ratio and ignition timing in a predetermined standard state after completion of engine warm-up are stored in advance as a reference actual compression ratio and a reference ignition timing. When the engine temperature is low or the intake air temperature is low, at the time of engine high speed operation, the actual compression ratio is made to increase over the reference actual compression ratio, while at the time of engine low speed operation, the ignition timing is made to advance over the reference ignition timing.