To provide a driving mechanism which can withstand the total value of increasing rolling torque and additional torque required with different circumferential speed rolling when rolling a new material such as super metal which requires heavy strain rolling at low temperatures with a rolling mill the diameters of an upper and a lower rolls of which are held as same as a conventional mill.

In the rolling mill the driving mechanisms of a pair of the upper and the lower rolls of which are arranged on the right and the left across the rolls, the difference of size is provided between the inside diameters of the bearings for supporting the rolls on the driving side and the anti-driving side and the bearings having a large inside diameter among them are arranged on the driving side of the roll and the bearings having a small inside diameter are arranged on the anti-driving side.