PURPOSE: To prevent the local abrasion of the reducing roll, and to carry out smooth and suitable rolling work for long period of time, by detecting the position of the strip, and by shifting the side guide to the correct position according to the amount of abrasion of the roll.

CONSTITUTION: When the computer 7 commands the new set position, the position comparator 8 compares the command position with the detected value of the position detector 9, and inputs the speed reference corresponding to the deviation to the speed controller 10. The speed controller 10 compares the detected value of the speed detector 11 with the reference value and inputs the current reference corresponding to this deviation to the current controller 12. The current controller 12 compares this reference value with the detected value of the current detector 13, and drives the thyristor 14 correspondingly to the deviation and controls the current of the motor 3. By rotating the motor 3, the screw rod 5 is rotated through the reduction gear 4; and by the rotation of the screw rod 5, the side guide 2 shifts laterally and longitudinally against the strip. As a result, the rolling work at the fixed position of the roll is prevented, and the local abrasion of the roll is prevented.