To adopt a proper rolling system in accordance with the material, size, shape, etc., of a material to be rolled by forming different passes at different position in the axial direction of the same rolling roll and selecting either one so as to perform roll processing.

A pair of corresponding guide rollers are provided in front of the pass, and it is preferably to arrange a pair of guide rollers to correspond to the pass of a box system in the vertical direction to the shaft center at a distance from each other in the direction parallel to the shaft center of the rolling roll and to arrange a pair of guide rollers to correspond to the pass of diamond-diamond system or diamond-square system horizontally in the direction parallel to the shaft center of the rolling roll at a distance from each other in the direction vertical to the shaft center. The rolled material can be rolled using either pass 14 to 16 by shifting the rolling roll 10 in the axial direction together with guide rollers 18 and 20.