To porivide a method for preventing the slip marks in a levelling roll, which occur during steel sheet straightening (roll straightening) using a leveller such as a hot leveller, and the leveller used for the method.

A clutch 8 is provided to each spindle shaft 10 of all levelling rolls 1. A reduction rate is set so as to generate a speed difference between a peripheral speed of each levelling roll and a steel sheet speed at a contact part between each levelling roll and a steel sheet. The speed difference is calculated in each of all levelling rolls. The clutch of the levelling roll, in which the speed difference exceeds a prescribed value, is disengaged. The levelling roll in which the clutch is disengaged becomes a non-driving state (free) so as to rotate corresponding to the steel sheet speed. Consequently, there is no speed difference between the levelling roll and the steel sheet at the contact part between them to thereby prevent the occurrence of the slip marks in the levelling roll.