PURPOSE: To burn methane gas safely and completely by a method wherein instable methane gas produced by the fermentation of organic material is burnt together with town gas.

CONSTITUTION: When an ignition switch 4 is fired, switch values 8, 9 are open at the same time and the town gas blows out of a pilot burner 3 through a town gas pipe 6. Further, methane gas blows out of a methane burner 2 through a methane gas pipe 7. Simultaneously, since an ignitor 5 works and sparks, at first the town gas blown out of the master burner 3 begins to burn. The flame of the town gas ignites the methane gas from the methane burner 2 and the methane gas also begins to burn. In the meanwhile, the ignition switch 4 is made ON and works as a pilot flame to help burn the methane gas. Accordingly, the methane gas burns completely.