To assemble a brush or the like to the center of a disc by projecting many projecting clicks leading in the scavenging body fitting surface side with the rotation of the scavenging body on the scavenging body fitting surface side of a holder disc.

Each of many projecting clicks 11 projected on the base 3F of a holder disc 3 has a click-like pointed tip bent L-shaped toward the rotating direction of a scavenging body DS. The head of a fastening member 4 is fitted in a fit-in hole Da of the scavenging body DS, and subsequently, the lower side of a screw part 3T of the holder disc 3 is a little screwed in a screw hole 4S. In such a state, before the fastening member 4 is completely fastened, the scavenging body DS is idled in the direction where each projecting click 11 does not lead in, thereby adjusting the center of the scavenging body DS. After centering, the fastening member 4 is completely fastened to clamp the central part of the scavenging body DS from above and below in a space up to the holder disc 3 and fix the same. When the scavenging body is rotated by a motor, the tip of each projection 11 leads in the upper surface side of the scavenging body DS made of non-woven fabric, the scavenging body DS is further firmly fitted.