PURPOSE: To make a simple structure by a method wherein a vaporization striking body composed of a hollow cylinder is fitted in an combustion cylinder composed of a cup-shaped cylinder, gasified oil is injected into the combustion cylinder to perform combustion.

CONSTITUTION: An air volume adjusting valve 17 is opened to feed a proper amount of air for fuel into the machine cylinder 7 having an injection nozzle device 15 therein. Subsequently, an oil volume adjusting valve 16 is operated to open the injection nozzle 13, resulting in that the oil is injected from the injection nozzle 13 with a certain injecting angle. Then, the oil passes through the air feeding cylinder 9 and strikes against the inner circumferential surface of the hollow cylinder of the vaporization abutting body 5. A part of the oil is abutted against the inner bottom surface of the combustion cylinder 4 and the atomized oil is fulfilled around it. Then, when the oil is ignited with an ignition electrode 14, the atomized oil is burnt to heat the hollow cylinder of the abutment body 5 and a partial surface of the combustion cylinder 4 to a high temperature in a short period of time and then the injected oil receives a latent heat of the vaporization abutment body 5 or the like and vaporized. With this system, it is possible to make a small-sized device.