To stable supply a liquid fuel to a carburetor over a long period by providing a vessel for supplying the liquid fuel to the carburetor and a standby vessel in standby state for supply.

A gas supply pipe 111, two vessels 150, 250 in which the liquid fuel is enclosed, and a material supply pipe 127 for supply in the liquid fuel to the carburetor 91 are provided. In the 1st vessel 150 to which a pressurized gas is supplied through a 1st gas line connecting pipe 113, a stop valve is provided at the midst of a 1st gas introducing pipe 151 as a 1st gas introducing valve 161 and a stop valve is provided at the midst of a 1st discharge pipe 153 as a 1st discharge valve 163, and also in the 2nd vessel 250 to which the pressurized gas is supplied through a 2nd gas connecting pipe 213, a stop valve is provided on a 2nd gas introducing pipe 251 as a 2nd gas introducing valve 261 and a stop valve is provided in a 2nd discharge pipe 253 as a 2nd discharge valve 263. As a result, the stable supply of the liquid fuel to the carburetor 91 is continued.