PURPOSE: To prevent the occurrence of a crack at the time when a roll body and a shaft member are fitted by integrally fixing both the roll body and the shaft member at two places via concentric taper surfaces, and by interposing ring members having equivalent taper surfaces between the roll body and the shaft member.

CONSTITUTION: A sleeve-shaped roll body 7 and a shaft member 11 are integrally fixed at least two places distant to each other in the axial direction thereof via taper surfaces concentric thereto. At one place out of these two places, both members are directly brought into contact with the taper surfaces. However, at the other place, ring members 9, 10 having a taper surface are interposed between the roll body 7 and the shaft member 11. Thus, the occurrence of a crack to be caused by the fitting of the roll body 7 and the shaft member 11 can be prevented.