PURPOSE: To prevent the rotation unevenness of an output shaft, to reduce the fluctuation of a mill and to improve the rolling performance and the surface quality of a product.

CONSTITUTION: A multistage cluster mill rotates an intermediate roll by engaging at least 2 teeth of output gears 15, 16 meshed with output shafts 13, 14 connected with an intermediate roll abutting on the work roll with an input gear 12 fitted to an input shaft 11 connected with a motor. The shaft diameter D of output shaft parts 13a, 14a of the central part to which each output gear 15, 16 is fitted is reduced in comparison with the shaft diameter D1 of other end parts 13b, 13c, 14b, 14c, the output gears 15, 16 and the output shaft end parts 13b, 14b are connected through couplings 17, 18, 26, 27 so that the torque transmitted to the output gears 15,16 is transmitted to the sides of the end parts 13b, 14b, of the output shafts 13, 14.