PURPOSE: To obtain long columnar bodies having different finished dimensions in a wire range with the same tool by adjusting the phase difference of eccentric rotation between an eccentric ring roll and a columnar body bearing device.

CONSTITUTION: When a housing is rotated while bearing a gear 9; the inner surface 13 of gear 9, whose center is different from the center of gear 9, rotates eccentrically to rotate eccentrically and eccentric ring roll 4 and its caliber D2. At that time, the center L of caliber D2 revolves with a radius LK around the center K of the outer circle of the housing and gear 9. When the ring roll 4 is moved in such a manner; a part of pipe, pressed and plastically deformed by the caliber D2, is advanced while being moved in the peripheral direction of the pipe, and the wall thickness of the whole periphery of pipe is reduced by rolling. At that time, the caliber center of a bearing ring-roll 5 is deviated from pass center line K in the same manner as the ring roll 4, to rotate the ring roll 5 by providing the phase difference between the rotations of ring rolls 4 and 5 to the roll 5, thereby changing the wall thickness of a finished pipe.