PURPOSE: To prevent secondary rupture from being generated with the movement of a steel strip by using a roll provided with a disk brake to a fixed roll and actuating the disk brake according to the passing speed of the steel strip to decelerate and stop the fixed roll.

CONSTITUTION: The fixed roll 5A provided with a disk brake is used for a fixed roll in a looper 2. A hydraulic pressure supply tube 19 is connected with the disk brake and a regulating valve 20 is closed and opened by a command from a main controller 10 to decelerate and stop the fixed roll 5A. A speed detector 21 is mounted on the shift of the fixed roll 5A and a signal for a detected actual speed of the fixed roll 5A is inputted into the main shaft controller 10. When the actual speed exceeds the reference speed, the disk brake is actuated to give a deceleration torque to the fixed roll 5A and the fixed roll 5A nearly synchronizes the passing speed of the line, decelerates and stops and the overrun of the fixed roll 5A is hindered.