PURPOSE: To prevent destruction of a driving layer by providing an outer cylinder having a flange at the top, a sharp crest at the bottom, and a hole in the neighbourhood of the crest, furnishing a shaft inserted into the outer cylinder and having a head at the top, installing a rod-shaped anchor member which is interposed between the shaft bottom and over the crest and whose bottom is confronting hole in the outer cylinder, and furnishing a spacer cylinder which is interposed between the outer cylinder flange and the shaft head.

CONSTITUTION: An outer cylinder 1 is made of steel and provided with two opposingly situated holes 1c on the diameter of the crest part 1d. An adhesive 3 is applied to the periphery of a shaft 2 made of steel, which is thus prevented from slipping off. When the head 2b of the shaft 2 is driven by hammer, the outer cylinder 1 and shaft 2 are consolidated by a spacer cylinder 6 made of plastic, and the outer cylinder 1 is driven till a flange 1b to stop there, and with another strike, the outer cylinder 1 is stopped moving by the flange 1b and compressed by the head of the shaft 2, and the spacer cylinder 6 is split and segregated. With a subsequent strike, attachment of adhesive 3 is released, and the shaft head 2b is driven to the surface of the flange 1b. At this time, the anchor member 4 of round metal wire emerges out of the hole 1c and intrudes into the underlay material B without destruction of the layer, and thus anchor is achieved.