Internal combustion engine controller

A target intake air mass and a target compression ratio are determined according to the operating condition of an internal combustion engine. A variable compression ratio mechanism (6) is controlled according to the target compression ratio. During this process, a knock limit intake air mass is determined from the actual compression ratio attained by the variable compression ratio mechanism (6), the smaller one of the knock limit intake air mass and the target intake air mass is set as the final target intake air mass and a variable valve timing mechanism (14) is controlled according to the final target intake air mass.