To attain high efficiency and improve exhaust gas quality at the same time by putting an internal combustion engine in action by self-ignition in a partial load area and by external ignition in a high load area, and producing a uniform fuel/air mixture in a combustion chamber in a self-ignition area.

An injection device 13 and an ignition device 14 are arranged at a peripheral part 15 of a piston recessed part 4 forming a combustion chamber 3, and an injection system of at least two kinds of pressure levels is connected to the injection device 13. In a cold starting stage, an internal combustion engine is driven by external ignition. In a partial load area, a compression ratio is raised to the value required for self-ignition of gasoline to attain excellent jet cracking of fuel. A control unit ECU controls injection timing according to ignition timing detected by an ignition sensor 17. Excellent uniformity of a fuel/air mixture can be attained by a widely known external mixture forming device. In a higher load area, the internal combustion engine is driven by external ignition. At this time, the control unit ECU actuates the ignition device 14 and supplies fuel to the injection device 13 under relatively low pressure.