A chemical solution supply part for supplementing the chemical solution to the chemical solution storage tank and a purge gas supply part for supplying N2 gas as a purge gas to the chemical solution storage tank are in communication with the chemical solution storage tank, and a first manometer serving as a pressure measurement part is arranged on the chemical solution storage tank. In addition, a drain piping is connected to a head portion of the plunger pump, and an automatically controlled air-bleed valve, which is an air-bleed mechanism, is arranged on the drain piping. On the other hand, a second manometer is arranged in the middle of the chemical solution supply pipe, and a front end of the solution supply pipe on the downstream side serves as an injection point for the chemical solution S.