PURPOSE: To uniformly roll the strip, and to improve the product quality, by arranging an intermediate roll between a work roll and backup roll on one side so as to be shiftable in the direction reverse to the widthways shift of the backup roll.

CONSTITUTION: The upper backup roll 7 integrally together with its roll chocks 8 and their connecting member 9 is made shiftable parallelly and reversely to the shifting direction of the intermediate roll 5, and besides, the lower backup roll 11 is supported by the cylinder 12 so as to be vertically shiftable. At carrying out the rolling work, the intermediate roll 5 is shifted to the right side so as to locate the left side edge of the intermediate roll 5 nearly above the left side edge of the metallic strip S. Moreover, the upper backup roll 7 is shifted to the left side by a required distance correspondingly to the said shift of the intermediate roll 5. Hereby, the load distribution between the upper work roll 11 and the intermediate roll 5 is canceled by the load distribution between the intermediate roll 5 and the upper backup roll 7, so that the metallic strip S is rolled with a uniform rolling load balanced between the left and the right sides.