PURPOSE: To improve yield in the rolling stage of an ingot by inserting a cooling bar-shaped body to the top of the ingot to solidify a molten steel just before the molten steel completes solidification or further providing notches to the periphery of a pouring or further providing notches to the periphery of a pouring port of a mold stool for bottom pouring in the stage of casting the molten steel, etc., into a bottom pouring casting mold and producing the ingot.

CONSTITUTION: The cooling bar-shaped steel material 3 is inserted into the top of the ingot 1 to solidify the unsolidified part without sinking into the deep part beyond the central segregation S just before the molten steel completes solidification in the casting mold in the stage of casting the molten steel into the casting mold and forming the ingot. A suitable number of the radial notches 7 of a suitable height are provided around the top end of the molten steel pouring port 6 of the mold stool 5 to form projections 8 in the bottom part of the ingot 1 in the case of bottom pouring casting. The side edge part is drawn from the central part in the upper and bottom parts of the ingot if such ingot is rolled. The generation of irregular end shapes in the upper and lower parts is thus obviated and the yield of the rolled product is improved.