PURPOSE: To prevent a driving-in layer from being inconveniently distrupted at driving-in time by making a thickness in the vicinity of the other end in an outer cylinder part which has a flange having a whirl-stop on one end and has a female screw inside thinner than the other outer cylinder part.

CONSTITUTION: In the case where an enclosing material A such as a roof tile is fixed to a surface of a lightweight bubble concrete backing material B, when a head 2b of a shaft 2 is hit by a hammer, an outer cylinder 1 stops by being driven in up to a flange 1b while the shaft 2 is put in as it is. Next, when the shaft 2 is rotated by a driver, since rotation of the flange 1b is stopped by a whirl-stop 1h, the shaft 2 is screwed in up to a surface of the flange 1b of the outer cylinder 1. An anchor member 4 is guided by an upward pointed head crest part 5c of a guide member 5, and comes out by breaking through a thin part 5d of the outer cylinder in order in its shaft direction, and enters the inside of the backing member B. Here, since positioning recessed part 2d exists on a lower end surface of the shaft 2, the shaft 2 and the axis of the anchor member 4 almost coincide with each other, and the anchor member 4 smoothly comes out of the outer cylinder, so that the periphery of a driving-in layer is not inconvenitently disrupted.