It is to suppress the excess pressure fluctuation at the time of initiation of the supplementary liquid medicament by controlling a filtration rate of the filter, to reduce the maintenance of the filtration accuracy. Filtered through a primary-side on-off valve (V ₁₎ and the outlet switching valve (V ₂₎ filter 46, the chemical liquid supplied from the chemical liquid bottle 13 by the opening and closing operation and the supply and discharge operation of a liquid pump in a chemical solution pump 50, at a post, and the discharge nozzle, the operating chamber 53 and the conduit (56) in fluid communication of a liquid pump in the liquid supply system for discharging from the unit 43, pressure sensor 59, flow meter 57 and the electro-pneumatic regulator (58 ) provided, and, equipped, and the pressure sensor detects the operating chamber of the pressure when opening the drug solution primary closing valve, at the time of starting the replacement of the a drug solution pump a control unit 60 for controlling the electropneumatic regulator operating the indeed, the exhaust flow rate detected by the exhaust from the flow meter, and the control unit controls the electro-pneumatic regulator so as to cause excessive pressure fluctuations at the time of initiation of the supplementary drug solution based on the detected pressure and the exhaust flow rate and adjusts the exhaust pressure.