PURPOSE: To roll with a driving method of merit according to rolling conditions by installing a driving machine built-in with a clutch capable of switching by the both methods of a mechanical tie method and an electric tie between the couplings at the motor side and a spindle coupling.

CONSTITUTION: When a pressure oil is poured into the chamber A of a cylinder 234, a shifter gear 218 for a switching clutch is moved in a direction B to connect with both gears of a fixed gear 216 for a lower driving roll and a connecting gear 212 for the lower driving roll and the rotation force is transmitted to the gear 212 for the lower driving roll from the fixed gear 216 for the lower driving roll and a mechanical driving method is made with connecting of the lower driving roll connecting gear 212 and upper driving roll connecting gear 112. On the other hand, when the pressure oil is poured into the chamber B of the cylinder 234, a shifter gear 218 for switching clutch is moved in A direction, the shifter gear 218 becomes non-connecting with the gear 212 for the lower driving roll, the rotation force is not transmitted to the connecting gear for the lower driving roll from the fixed gear for the lower driving roll and an electric tie driving method is made.