PURPOSE: To improve the yield of products by disposing a roll which can roll the angle corner part at the transverse end of a material to be rolled before hot rolling.

CONSTITUTION: The hot rolled material (slab) 1 is edged by using the edging device. The roll (trapezoidal caliber roll) 8 which can roll the angle corner part at the transverse end of the slab 1 is, thereupon, disposed. The angle corner part of at the transverse end of the slab 1 is smoothed by this roll 8. The freshly generated angle corner part at the transverse end of the slab is limited to the edge part in the transverse direction of the slab in the ensuing edge rolling. The amt. of trimming is limited in this way even if scabs by the angle corner part are generated.