PURPOSE: To prevent loose winding of a strip on a work roll and to improve the productivity by bringing a diameter of a work roll of the outlet side of a rolling mill to be larger than that of a work roll in the inlet side of the mill.

CONSTITUTION: Work rolls 1, 2,...n+1 are stacked in one vertical line and backup rolls 11, 12 are installed on the uppermost and lowermost positions. A strip S is carried by about a half circle along the work roll 2 after passing a rolling pass P1 and then the strip S sequentially passes through a rolling pass P2, the work roll 3... and finally passes through a rolling pass Pn. As for multi-stacked work rolls, a contact arc length at the outlet side of a rolling mill is made to be longer than that at the inlet side of the mill. Hence, a contact area at the outlet side is larger, so that slips of the strip S are hardly generated in that area and stable rolling is continued.