PURPOSE: To connect a plurality of drain piping including extension easily by attaching a drain adapter provided with a plurality of drain holes in such a way as surrounding a shaft part, having a communication part including a radial opening, of an oil filler plug screwed into a filler opening of an oil tank.

CONSTITUTION: An oil feeder for various kinds of hydraulic equipment such as a tractor and the like is provided with an oil tank 6, and an oil filler plug 25 having a head 24 is fitted in to a filler opening 23 of the oil tank 6 by screwing its shaft 26. In order to return drain oil from a plurality of hydraulic equipment to the oil tank 6 by using a common filler opening, a communication part 29 composed of an axial passage 27 and a radial opening 28 communicating therewith is formed on a shaft part 26 of the oil plug 25 and a drain adapter 31 having a plurality of drain holes 30 which surround the shaft part 26 and are communicated with the communication part 29 are sandwiched between the head 24 of the fuel plug 25 and the tank 6 for attaching. The drain holes 30 are provided with quick couplers 34 to which return pipes 35 for each hydraulic equipment are connected respectively.