PURPOSE: To improve a bonding strength by pressing two outer rings in the axial direction of a shaft, fitting them into a sleeve in the condition, in which a pre-load is given and providing a cross section rectangular groove for adhesives between the outer ring and the sleeve.

CONSTITUTION: A shaft 7 is held at the outer ring of 9 through a ball 10 and the shaft 7 and a unified upper cylinder 1 are freely rotated for a lower cylinder 3. The outer ring 9 is fitted into a sleeve 8, a groove 12, in which the cross section in rectangular, is provided between both at the lower edge and by inserting adhesives to the groove 12, the outer ring and the sleeve are fixed. The sleeve 8 is fixed by bonding to the lower cylinder 3. Thus, a bonding area is increased, a bonding strength is improved, and at the time of the cutting after the bonding, the sleeve and the outer ring does not slip off.