PURPOSE: To match the number of revolution by driving transmission shafts with two motors through an addition gear transmission and taking two transmission shafts the fixed ratio of the number of revolution of which as a rolling path which is arranged on the line integrated in adjacent roll stand groups.

CONSTITUTION: The transmission shaft 6 of the addition gear transmission stage 1 is branched to the transmission shaft 7 through a spurgear transmission stage 5 for converting the number of revolution. In the roll stand 2, the transmission shafts 6, 7 the ratio of the number of revolution of which is respectively fixed in accordance with the use can be connected or separated with coupling members 8, 9. The fixed ratio of the number of revolution of the two transmission shafts 6, 7 and reversal of the direction of revolution are attained with the spur gear transmission stage 5 for converting the number of revolution. In the case the transmission shafts 6, 7 on the secondary side are used for connecting a finishing roll stand 2, corresponding spur gear transmission stage 5 can be designed because their rotational torques are relatively smaller and the additional cost for the rolling path is made smaller in accordance with that.