PURPOSE: To remotely control the change of roll width by making the rolling width of the horizontal roll of a universal mill arbitrarily variable on-line and additionally making into a structure that the roll shaft, chucks and device for changing rolling width can be easily attached and detached.

CONSTITUTION: A motor 25 is operated and a nut 22 for adjusting width is revolved in a roll chuck 4 on the operation side. The movement of this nut for adjusting width in the axial direction of roll is restrained with a fixed block 15 and press plate 29 which are fixed to the roll chuck on the operation side. Each of slide blocks 14, 20 on the operation side and drive side which are joined with a screw which has the same pitch and different direction of screw cutting from the nut 22 for adjusting width are relatively moved in the axial direction of roll. The slide block 14 on the operation side is connected to the roll shaft 10b and roll barrel 9b on the operation side through a thrust bearing 13. The slide block 20 on the drive side is connected to the roll barrel 9a on the drive side through a thrust bearing 18, radial bearing 19, connecting block 17, connecting bolt 16 and the roll shaft 10a on the drive side. So the length W of roll barrel can be freely adjusted.