PURPOSE: To ease both maintenance and inspection by constituting the system in such a manner that an indicating means is lit by means of a control signal, which is output when the flow-rate or the pressure is controlled.

CONSTITUTION: The first deviation computing part 11 computes the difference between the actual discharge quantity Qf, which comes from a discharge quantity sensor 5, and a target discharge quantity Q of a target discharge quantity setting device 7. Then, the computing part 11 outputs the difference as an output. The second deviation computing part 12 computes the difference between the actual discharge pressure Pf, which comes from a discharge pressure sensor 6, and a target discharge pressure P of a target discharge pressure setting device 8. The computing part 12 outputs the difference as an output. An indication lamp 31 is connected to a signal outputting route that is led to a deviation conversing circuit 11c in the first deviation computing part 11, and the indication lamp 31 is lit when a flow-rate control signal is issued. Similarly, when a pressure control signal is issued, the indication lamp 32 is lit.