PURPOSE: To produce an steel ingot having sound casting structure as the basic material and to obtain a uniform product by plastic-working after solidifying molten steel poured in an ingot case while stirring with a stirrer composed of refractory.

CONSTITUTION: At the time of solidifying the molten steel 4 poured in the ingot case 5 while stirring with the stirrer 1 composed of the refractory, the dendrite can be shorn on the way of growing the primary and the secondary dendritic arms, and the shorn dendrites become new crystal nuclei and therefrom, the new dendrites are grown. The primary and the secondary dendritic arm spacings become small by repeating, and the segregation is reduced and also, the crystal grains are fined. Particularly, at the time of solidifying a high alloy steel containing a large quantity of carbide-making elements in the large sized ingot, the solute is concentrated during solidifying, and string ghost segregated as linear-state by flowing the molten steel at this part or inverse-V segregation zone is formed.