PURPOSE: To reduce the connecting force by arranging an intermediate ring and ball arrays between taper rings and pressing the taper rings to the intermediate ring by a clamping bolt to bite into the balls in the taper rings and the rotary body and rotary shaft.

CONSTITUTION: A rotary shaft 2 is inserted into the shaft hole 10 in the center of a rotary body 1. Taper rings 3, 4 and an intermediate ring 5 are arranged between the shaft and the body. Ball arrays 6, 7 constituted by balls 61, 71 are disposed between the taper rings 3, 4 and intermediate ring 5. Each diameter of taper rings 3, 4 is reduced or expanded respectively on the side of the intermediate ring 5 to form convex or concave taper surface 31, 40. The taper rings 3, 4 are clamped by a bolt 8. In this way, it is possible to connect the rotary body 1 and rotary shaft 2 with reduced force due to the wedge effect of the ball arrays 6, 7.