To provide a fastener which is stably attached to a skin material regardless of the state of a sheet pad.

A fastener includes: a shaft body 11 which is inserted into a slit like mounting hole 2 formed on a skin material 1 and has a rectangle shaped first holding body 20, elongated in one direction and located at one end, and an engagement part 40 engaging with a wire harness and located at the other end part; a second holding body 30 having a through hole 31 in which an outer peripheral surface of the shaft body 11 loosely fits; and a holder 15 which is disposed at an outer peripheral part of the shaft body 11 and holds the second holding body 30 at a holding position where the second holding body 30 may hold the skin material 1 in cooperation with the first holding body 20.