PURPOSE: To maximally utilize the capacity of an electric motor, by retracting a cylinder according to a discharge load condition of a fluid, and driving a plunger engaged with the cylinder under an optimal engaged condition according to a desire flow rate and pressure.

CONSTITUTION: A pinion 23 is mounted on a rotating shaft of an electric motor 22 fixed to a body 21 of the device, and is meshed with a spur gear 24. An eccentric cam 27 is rotatably provided at an eccentric position of the spur gear 24, and a recessed cam follower 29 is slidably engaged with the cam 27. The cam follower 29 is mounted to a slider 31 integrally formed with a plunger 33. The slider 31 is reciprocated by the rotation of the motor 22 to pressurize a grease supplied from a grease tank 43a to an inlet 42 and discharge the same through a check valve 50. At this time, a cylinder 46 enclosing a front end portion of the plunger 33 is retracted against a spring or the like according to a discharge load condition of the grease to thereby automatically adjust the flow rate and pressure of the grease.