A compression ignition internal combustion engine in which the temperature and pressure in the combustion chamber are increased to self-ignite an air-fuel mixture with the compressive operation of a piston after closing of the intake valve. An ECU [1] controls injection timing of the pressurized air depending on the ignition timing. Self-ignition timing can be controlled to a proper timing in a wide engine operating range with respect to a load and a revolution speed without substantially changing the shape of the combustion chamber.