PURPOSE: To stably transfer liquid by providing a gas chamber on a portion branched from a discharge part side pipe line of a constant rate pump, providing automatic valves for supplying and discharging gas in respect to the gas chamber, and controlling the automatic valves according to detection results of pressure fluctuation of liquid in the pipe line.

CONSTITUTION: An ion exchange resin column 2 which produces pure water is regenerated, a transferring device supplies hydrochloric acid or caustic soda as chemicals in a liquid storage bath 1 to a treatment bath 2 by means of a constant rate pump 3. In such a case, a gas chamber 5 is provided on a portion branched from a discharge part side pipe line of a constant rate pump 3, while a check valve 4 is arranged between the gas chamber 5 and the pipe line. An automatic valve 6 and 7 are provided on the gas chamber 5 respectively for introducing gas into the gas chamber 5 and discharging liquid therefrom. Pressure fluctuation of liquid in the pipe line is monitored by a pressure sensor 8. When a specified width is detected, command is supplied to the automatic valves 6 and 7 for eliminating pulsative motion of transferred liquid.