PURPOSE: To easily execute a sound surface treatment at the necessary part by inner-chilling the inner-chill material composed of the material easy for surface treatment simultaneously with casting the main body of an aluminum die casting article and treating the surface thereof thereafter.

CONSTITUTION: The inner-chill materials 4, 7 are formed in advance and fixed with their arrangement at the specified position of the inner part of the die used in case of casting the main body 2 of an aluminum die casting article. And an Al alloy in a molten state is press-fitted into the die. At the contact part of the Al alloy and the material 4, 7 the latter are melted and the latter and main body 2 are metallurgically joined. Thereafter, the main body 2 to which the material 4, 7 are joined is taken off from the die and subjected to the surface treatment by an anodic oxidation. A sound surface treatment is thus executed easily on the material 4, 7 part for which the surface treatment of the main body 2 is necessary.