PURPOSE: To improve the work efficiency by applying a dispersing liquid of a tellurium metal to a forming surface of a mold whose main component is a ceramic sand, impregnating the forming surface of the mold with a poured molten metal, and forming a coating layer on the surface of a casting at the same time as casting.

CONSTITUTION: A mold 1 and a core 2 contained in a molding flask 5 are formed by mixing a ceramic powder whose main component is zircon together with a binder material, and ramming them to a prescribed shape. Also, a dispersed liquid of a tellurium metal is applied uniformly by a prescribed quantity to each forming surface of a cavity 3 and the core 2. Subsequently, when a molten metal is poured into the cavity 3 through a sprue 4, the molten metal is penetrated to a prescribed depth into the inside of the mold 1 by an inpregnation accelerating action of the tellurium metal. In this case, a cast iron grain (f) of the molten metal goes in between ceramic particles C of the mold 1, therefore, after elapsing a prescribed cooling time a casting on which a ceramic coating layer 9 is laminated can be fetched.