PURPOSE: To increase ratio of a pressure receiving area so as to obtain a high pump delivery pressure by providing constitution such that closed space, in which an operating rod of a reciprocating actuator is vertically moved, is opened to the outside from an upper end of the actuator by utilizing through holes, provided in the operating rod, and an operating fluid discharge pipe.

CONSTITUTION: In this pump device in which a reciprocating pump 81 is provided in a lower side of a reciprocating actuator 11, the actuator 11 is connected to the pump 81 by pump connecting tubes 76, 77 of small and large diameter. In the reciprocating pump 81, a pump rod 83 of small diameter is connected to a lower side of an operating rod 17 of the actuator 11 to provide a pump piston 89 of small diameter, vertically moved in a pump cylinder 88, in a lower end part of this pump rod 83. A material delivery port 75, provided in a lower part of the actuator 11, is connected to the pump cylinder 88 of the pump 81 by a material lift passage 80 between the tubes 76, 77, and operating rod vertically moving space 65 inside the small diameter tube 76 is connected to the outside via through holes 64, 63 and an inner hole 62 provided in the operating rod 17.