PURPOSE: To extend the life of a casting mold by covering part of the inside surface of the casting mold in a bottom pouring method with a steel plate.

CONSTITUTION: The casting mold 3 for the bottom pouring method is installed on a lower molding board 1 and an upper molding board 2 forward with a runner 4 and a molten steel m is cast through said runner 4 into the mold 3. The long side of the mold 3, i.e., the range of ≥500mm, more particularly 500W1,000mm upper than the bottom end of the inside surface of the long wall 5 is covered by the steel plate 6 and thereafter the molten steel m is cast into the mold 3. The steel plate 6 may be attached by any method including nailing, riveting and adhesive bonding.