PURPOSE: To efficiently perform the rough rolling of slab in a short rough rolling line by arranging a sizing press for edging slab, roughing mill and coil box successively on the outlet side of a heating furnace.

CONSTITUTION: A slab S which is heated to a prescribed temp. in the heating furnace 1 is taken out of the heating furnace 1, edged into a prescribed width with the sizing press 2 for edging slab, reversing rolled several times with the roughing mill 4, made into a metallic band plate P with a prescribed thickness and coiled into a coil with the coil box 5. The coiled metallic band plate is properly uncoiled with the coil box 5 and finishing rolled. Then, the edging quantity of the slab S can be increased, because the slab S is edged with the sizing press 2 for edging slab. Therefore, the interval of the width of slab which is manufactured with a continuous casting machine which is installed on the upstream side of the heating furnace 1 can be enlarged, it requires fewer kinds of slab which is manufactured with the continuous casting machine, the frequency of mold change can be decreased and production efficiency can be improved.