To provide a method for solving the problem that the shaft part which is a thrust part in the shaft end part of a roller is damaged because the roller metal is worn out and the center position which is the axial center of the roller is shifted down, in a roller straightening machine.

In the roller straightening machine for steel, a thrust self-aligning roller bearing 1 incorporated in a bearing case 2 is made slidable while coming in contact with right and left end part plates 4, and when the center position of the roller 7 is lowered due to the wear of the roller metal 8, the force in the radial direction is intended not to apply to the shaft part 7c of the thrust part in the shaft end part 7d of the roller 7, thereby the roller 7 is rotated while holding the thrust load with the thrust self-aligning roller bearing 1, for preventing the damage of the shaft part 7c of the roller 7 due to the wear of the roller metal.