To provide a method for straightening, by which the wear of a roll is suppressed, a setup changing time is shortened to improve the purifying efficiency when straightening the steel stock such as tubes and bars.

The method of straightening the bends of the steel stock is obtained by using a cemented carbide straightening roll in which the roll material is a tungsten carbide-cobalt (WC-Co)-based sintered object (superhard alloy). In the method of straightening, the hardness of the cemented carbide straightening roll is HRA 85-87. The straightening method is especially effective when the materials to be straightened are high strength materials such as a steel tube for automobile air bags.