PURPOSE: To prevent a metallic oxide from floating on the surface or settling into a molten metal by liberating from a base metal by incorporating the particles of the metallic oxide into the molten metal and installing a chiller into the cavity of a casting mold.

CONSTITUTION: An inert gas is passed in a passage 9a and a vibrator 9c operates just before a molten metal A is poured from a ladle 8 into a sprue 7. Then, a prescribed amt. of metallic powder M is added into the molten metal and is fed together with the molten metal into the sprue 7 to fill the inside of the cavity 2. Part of the molten metal is quickly cooled by the chiller 3 in this stage and is thereby quickly solidified; on the other hand, the molten metal is replenished from risers 4, 5 into the cavity 2 in the same manner as heretofore to prevent the generation of a shrinkage cavity and therefore, the metallic oxide incorporated into the base material is retained in the base metal without being liberated therefrom.