To detachably attach a fixed component, without ruining a fastener, such as blind rivet.

This fastener 10 comprises the blind rivet 13, a first fixing member 11 for receiving the blind rivet, and a second fixing member 12 detachably engaged with the outside of the first fixing member. The blind rivet comprises a hollow cylindrical rivet body 17, formed with a flange in its one end and a mandrel 18 which extends penetrating the rivet body. The first fixing member is provided with a hollow shaft part 25, a seat part 30, extending radially outward from one end part of the shaft part and seating the flange of the rivet, and a retainer part 26 which axially extends, from the outer circumference of the seat part and receiving the flange and the mandrel of the rivet body. The second fixing member is provided with a flange part 41 and a hollow retainer part 42, extending axially from the inside diameter part of the flange part and receiving the first fixing member.