PURPOSE: To enhance the reliability of the device by providing mechanical stopper means for prohibiting the contact of spindle supporting members and a roll-driving spindle at the time of rolling.

CONSTITUTION: The spindle supporting members 10 are placed in the non- operation positions parted from the roll-driving spindle 4 at the time of rolling and are moved to the operation positions where the members come into contact with the roll-driving spindle 4 and the spindle 14 is supported by these members 10 at the time of changing the roll 2. The spindle supporting members 10 are driven between the non-operating positions and the operating positions by actuators 12. The contact of the spindle supporting members 10 and the roll- driving spindle 4 at the time of rolling is, thereupon, prohibited by the mechanical stopper means 13. The generation of heat by the contact of the spindle supporting members and the spindle during high-speed rotation is surely prevented.