PURPOSE: To improve combustion efficiency and to allow an engine to exhibit its output to the maximum possible extent with a little fuel by fixing a suitable number of catalyzer device in a suitable form to the tip end of a combustion injection nozzle or to the inside of an intake opening or an exhaust opening in a cylinder of the engine.

CONSTITUTION: A suitable number catalyzer device 5 with a suitable from and size are provided on the tip end of a combustion injection nozzle 2 or the intake opening 3 or the exhaust opening 4 in an engine cylinder 1. When fuel is injected into the cylinder 1 from the injection nozzle 2 and expoded, gaseous body which includes pre-combustion fuel and passes through the catalyzer 5 in a moment is given full combustion to the included pre-combustion material during the time it passes through the catalyzer 5 forward and backward. Therefore, combustion temperature is extremely increased and combustion efficiency is improved. Consequently, fuel is injected with less mixing ratio of fuel against air than the conventional ratio and it is given full combustion, allowing an engine to exhibit its output to the maximum extent, thereby an engine with high combustion efficiency can be obtained.