PURPOSE: To eliminate heavy work for changing roll, to improve safety, and to perform speedy operations by installing a robot having a roll attaching-and- detaching function and a robot having a roll cover attaching-and-detaching function and alternately actuating those robots to attach and detach a roll and a roll cover.

CONSTITUTION: A roll attaching-and-detaching robot 1 has an articulated arm 4 and a traveling device 3. A support shaft and a hand 7 are rotatably connected on the top of the arm 4. The support shaft 5 is provided with a hydraulic piston 10 related to the hand 7 combining a hydraulic cylinder 7a. A clamp mechanism locking with a lock part 14a is formed when a clamp part 13 on the top of the support shaft 5 is inserted into a groove 14 of an insertion hole of a driving shaft 12 and is rotated. A roll cover attaching-and-detaching robot 1a has the same articulated arm 4a and the same traveling device 3a as those of the robot 1. The top of the arm 4a is connected to a hand 23 consisting of a piston 26 for a clamp gripping a cover 25, a clamp claw 27, and a nut runner 28 fastening and removing a set bolt 24.