To enable the continuous adjustment of the total reduction of area by providing a first stand with anther motor from a motor transmitting roll drive to the other stands, and adjusting the reduction of area independently of the revolving speed of rolls.

Since the motor 8 for driving the rolls in the first stand 18 and a motor 9 for driving the rolls in stands 20, 22 and 24 other than the first stand 18 are different from each other, the revolving speed of the rolls in the first stand 18 and the revolving spead of the rolls in the stands 20, 22 and 24 other than the first stand 18 can be independently controlled. Consequently, the adjustment of the reduction of area in the first stand 18 and that in the second stand 20 can be independently executed. Therefore, the total reduction of area can be continuously adjusted, if necessary. Also, it is widely adiusted without exchanging a gear on a distribution gear device 7 side by multip lying the speed moderation ratio of a transmission means 37 with a roll rotation ratio by the distribution gear device 7.