To provide a gas control type quantitative liquid feeder in which a prescribed amount of a liquid is intermittently supplied at the prescribed timing without being affected by the dimension and the layout of a pipeline.

A supply port 21a is opened in the wall of a vessel 21, 22 which is capable of holding a predetermined amount of a liquid and a check valve 23 closing the supply port is provided. Furthermore, a gas supply pipe 13 and a gas discharge pipe 11 extending into the vessels are provided. The vessels are immersed in the liquid to be supplied and the check valve is opened by pressure of liquid and the vessel is filled with the liquid flowed in through the supply port. When a pressurized gas is introduced into the vessel through the gas supply pipe, the liquid filling the vessel is discharged to the outside through the gas discharge pipe.