PURPOSE: To prevent a rust prevention coating layer for coating the wall surface of a male screw inserting hole provided in a fastened member for inserting the male screw like a bolt, from breakage caused by rubbing of the male screw.

CONSTITUTION: While a washer 1 is provided in the planar part 1a with a hole 1b, a rising-up 1c part rises from the planar part 1a on the peripheral edge of the hole 1b. By inserting the rising-up part 1c into a male screw inserting hole 3a of a fastened member 3, the rising-up part 1c is interposed between the male screw 2 and the male screw inserting hole 3a of the fastened member 3, so that a rust prevention coating layer such as painting, plating, etc., formed on the wall surface of the male screw inserting hole 3a can be prevented from breakage caused by the rubbing of the male screw 2.