A liquid chemical supply system that performs accurate pressure feedback control and controls the discharge flow rate of liquid chemical with high precision, even when the pressure setting value of the operation pressure differs due to changes in the type of liquid chemical, includes a pump having a pump chamber and an operation chamber separated by a diaphragm comprised of a flexible membrane. The intake and discharge of liquid chemical is performed in accordance with the change in pressure inside the operation chamber. An electro-pneumatic regulator supplies operation gas pressure to the operation chamber. A plurality of pressure sensors having different pressure detection ranges is provided for detecting the operation gas pressure. A controller selectively employs any of the detection results of the plurality of sensors in accordance with the pressure setting value of the operation air that is set for each use, and performs pressure feedback control.