PURPOSE: To perform stable control of a delivery flow rate on the whole of a pump throughout the whole area of a spool stroke by providing a plurality of sets of valve means (spool valves) for controlling the opening of a suction passage in a state to change opening control characteristics, in a variable capacity pump, such as a radial piston pump.

CONSTITUTION: In a radial piston pump 1, spool valves 31-1 and 31-2, serving as a valve means, connected to suction circuits 30-1 and 30-2 and capacity control circuits 40-1 and 40-2 have springs 37-1 and 37-2, respectively, being different in characteristics, such as a spring constant and a set force. By properly setting the characteristics of the springs, the characteristics of a spool opening area responding to a spool stroke for secondary curveform characteristics (desired characteristics) on the whole of the pump 1. Thus, the characteristics of a delivery flow rate to a spool opening area are brought into an approximately linear state and stable control of a delivery flow rate can take place.