To efficiently and surely executing lubrication and oil feeding to a riveter device with a simple structure and operation by operating an oil piston so as to retreat to the position maximizing the capacity of an oil chamber with an external operation.

The oil piston 211 so reciprocated slide within an oil cylinder 210 by operating about ten times a push button 810 as a trigger, and the oil is poured from an oiler into the oil chamber 212 of the oil cylinder 210 by a pumping operation. And the chip end of a maintenance bolt is screwed into the screw hole 253 of the oil piston 211, the maintenance bolt is grown outside by hand, and the oil piston 211 is moved up to the retreat end. By this way, plenty of oil containing no air is rapidly and surely filled into the oil chamber 212. Thereafter, the oiler, a coupling and the maintenance bolt are removed, and a maintenance plug 255 and an oil feeding plug 251 are re-installed.