PURPOSE: To enable a sufficient evaporizing combustion even if the height of an entire burner unit is made thin by a method wherein the combustion oil is atomized into a combustion cylinder through each of the splashing parts arranged at a plate-like evaporizing inner cylinder and an injection gas branch cylinder which is integrally rotated at an outer circumference of the inner cylinder.

CONSTITUTION: Upon combustion, at first, a plate-like evaporizing inner cylinder 5 and a humidifying outer cylinder 6 are rotated at a high speed through a rotary shaft 4, and at the same time, the combustion air is blown from the air passage 3 to mixture gas passage 11 and injection passage 10, and then oil is sent from an oil feeding pipe 22 to an oil defuser 20. The oil is moved in the plate-like evaporizing inner cylinder 5 and injected to a branch wall 13 in an injection gas separating cylinder 12 during its rotation from splashing end 19. The oil is injected into a combustion cylinder 1 through a splashing part 15 and ignited through a spark plug 23. When a temperature in the humidifying gas passage 11 rises due to combustion flame, the combustion oil in the plate-like evaporizing inner cylinder 5 is evaporated and gasified during its flow, and then the gasified oil is mixed with the combustion air and injected from main injection flame passage 17, and finally injected from sub-injection flame passage 18.