To compensate for a decrease in discharge flow rate that occurs in an early stage of a discharge stroke in a non-pulsating pump.

The amount of discharge flow rate qA decreases in an early stage of a discharge stroke Pd of a diaphragm pump configuring a non-pulsating pump (Ss). This decreased portion Ss is compensated by increasing the amount of discharge flow rate qB of another diaphragm pump (Sc). That is, the decrease in the discharge flow rate that occurs in one diaphragm pump is compensated by increasing the the discharge flow rate of the other diaphragm pump at the same timing as the occurrence of the decrease, which enables the non-pulsating property of the discharge flow rate to be maintained as a whole non-pulsating pump.