To reduce the delivery rate of hydrocarbon, and improve an efficiency by supplying mixture of an air-fuel ratio adapted to an engine operating condition in a wide engine operating region to a combustion chamber.

An internal combustion engine is provided with an subsidiary chamber 17 communicated with a main combustion chamber 16, an injection means 18 for injecting mixture to the auxiliary combustion chamber directly and intermittently, and ignition means 36, 37 arranged on the subsidiary chamber 17. Each capacity ratio between the subsidiary chamber 17 and the main combustion chamber 16 is se within 2:8 to 6:4. The injection means 18 formed as mixture injection means, is composed of an accumulating chamber 19 in which pressure air is filled and which is arranged adjusted to the subsidiary chamber 17, an opening/closing valve 32 for communicating the accumulating chamber 19 and the subsidiary chamber 17 with each other freely to open and close, and a combustion injection valve 21 for injecting fuel to the accumulating chamber 19.