Abstract: Grease fed from a grease tank 10 to a metering force feeder 22 is fed into an injection cylinder 30 after the weight of the grease is precisely measured, and the total amount of the grease in the injection cylinder 30 is injected from the nozzle 34. The nozzle 34 can advance toward an electric motor 60. When the nozzle 34 advances, a first packing 50 and a second packing 52 provided on a tip-end face 34a closely contact to an outer ring 66a and an inner ring 66b of a bearing 66, respectively. In the condition, when the grease is injected from an injection hole 34b, the grease is pushed into an operation space of rolling elements 66c of the bearing 66. A grease pocket 68 is also filled with the grease.