To accurately position a rolling roll at the center position of a shaft.

The roll assembly 10 includes a supporting shaft 12 having a taper part 14 extending from an abutment 16 to an end part 20. A taper sleeve 36 is inserted between the cylindrical bore 34 of a ring-shaped roll 26 and the taper part 14. A load ring 40 which is movable in the axial direction is situated on a distant side from the supporting shaft 12 of the roll 26. A disk spring 44 is inserted between the load ring 40 and the sleeve 36 and a clearance 56 between the load ring 40 and the roll 26 is formed by its elastic force. With a a roll retainer 50 attached to the end part 14 of the shaft, the clearance 56 is closed by acting so as to abut on the load ring 40 and through an elastic member and also the taper part of the sleeve 36 is wedged in the axial direction between the taper part 14 of the shaft and the cylindrical bore 34 of the roll.