PURPOSE: To improve cooling efficiency and to execute uniform cooling by providing a cooling water storage chamber formed of a drum, shaft and side plates into a roll and disposing holes for leading in and out of cooling water to the axial side part thereof.

CONSTITUTION: The entire space enclosed by the drum 4, the shaft 1 and the side plates 2, 3 is utilized as the cooling water storage chamber 15. The cooling water introducing hole 8 provided to the shaft 1 is opened through a water feed port 16 to one side of the chamber 15 and the cooling water leading out hole 10 is opened through a water discharge port 17 to the other side of the chamber 15. The cooling water supplied through the hole 8 fills the chamber 15 and thereafter the water is discharged at the rate equal to the supply rate through the hole 10. The cooling capacity is therefore increased by the cooling water filled in the chamber 15, by which the cooling efficiency is improved and the inside surface of the drum 4 is uniformly cooled. The cooling efficiency of the roll is thus improved and the uniform cooling is executed.