PURPOSE: To obtain the excellent revolving/holding capacity by putting a projected bar connected to an elastic member into a holding tool which holds with pressure a flat plate type information recording carrier fitted into a rotary shaft body and then fixing the holding tool to said shaft body with frictional force by means of said projected bar in a fit mode.

CONSTITUTION: Two holes 11, for example, are formed inside a holding tool 1 and toward th center of the tool 1, and a ball-shaped projection matter 13 containing an elastic matter 12 like a spring, etc. is put into those holes 11 respectively. These matters 13 are semifixed by screw 14, etc. The pressing force of the matter 13 can be varied by changing the position of the screws 14 and therefore by the expansion/contraction of the spring. Such a tool 1 is set with pressure into a rotary shaft body 2 containing a disk D. Thus it is possible to obtain the holding power that can withstand the revolution by the force of the matter 13 which presses the circumferential surface of the body 2. Thus the center hole of the disk D in never injured since the body 2 has no projection. In addition, the body 2 can be easily processed with simple attaching/detaching of the body 2.