To provide a pre-combustion chamber system capable of performing superior ignition of fuel-air-mixture gas in a pre-combustion chamber even under an operation of theoretical mode of a large volume engine accompanying with substantial recycle of the exhaust gas without showing any safety risk caused by the presence of the ignitable fuel-air-mixture outside the combustion chamber.

The system includes a pre-combustion chamber volume part 4 to cause ignitable fuel-air-mixture gas to be ignited with an ignition device 6 that can be arranged in particular in a pre-combustion chamber system 1, the pre-combustion chamber system 1 is provided with a fluid moving passage 5 connecting the pre-combustion chamber volume part 4 with a main combustion chamber of an internal combustion engine. The pre-combustion chamber volume part 4 includes an ignition region 3 and a fluid moving region 2 at least partially divided by an intermediate wall 9 against the ignition region 3. The fuel-air-mixture gas is ignited in the ignition region 3, the fluid moving passage 5 is opened inside the fluid moving region 2 and an air supplying passage 8 is provided and preferably the compressed air is supplied to the fluid moving region 2 by the air supplying passage 8.