PURPOSE: To reduce the size of an installation and to improve sheet thickness accuracy by disposing plural rolls in series, constituting supporting rolls with rolls at both ends and one central roll and executing simultaneous rolling of plural passes at different rolling speeds.

CONSTITUTION: The large-diameter supporting rolls 4W6 respectively supported by journal boxes 1W3 are assembled into a housing 7. The small-diameter rolls 13W16 respectively held between the rolls 4, 5 are vertically movably disposed in series. The roll 4 is screwed down by a screw 8 and the roll 6 by a screw- down cylinder 10, respectively in the stage of rolling a strip S. The strip is simultaneously and constantly rolld in plural passes at the fixed draft between the rolls 4 and 5 and one pass of shape controlled rolling is made possible between the rolls 5 and 6. The number of the rolls is thereby decreased and the size of the installation is reduced; in addition, the sheet thickness accuracy is improved.