To completely remove a harmful material from a material supply line by providing stop valves respectively in a discharge pipe, a material line connecting pipe and a material supply pipe and providing stop valves also in a by-pass pipe and a connecting pipe.

The liquid material supply device is for charging a liquid fuel enclosed a vessel main body 41 with an inert gas to a carburetor 75 through to material supply line 21 and is provided with a harm removing device 50. That is, an exhaust pipe 39 is closed by closing valves 151, 153 of the harm removing device 50 and a pressurized gas is fed to the vessel main body 41 by closing the valve 131 of the by-pass pipe 31 and the valve 135 of the connecting pipe 35. The liquid enclosed in the vessel main body 41 is charged to the carburetor 75 through the discharge pipe 23, the material line connecting pipe 25 and the material supply pipe 527, and at the time of exchanging the vessel, a material such as silicon tetrachloride remaining in the inside of the discharge pipe 23 and the material line connecting pipe 25 is surely removed by opening the valve 135 provided in the connecting pipe 35.