PURPOSE: To prevent the generation of shrinkage cavities and deformation by scooping out the molten metal of the part corresponding to a thick wall part gradually at the same instant when solidification begins from the part in contact with the molten metal poured into a mold.

CONSTITUTION: Molten metal 2 of a low m. p. metal, for example, zinc alloy, is poured into an open type mold 15. The molten metal 2 begins to solidify from the parts in contact with the mold 15 with lapse of time, but the part 17 near the center of a thick-walled part 6 still maintains a fully molten state. Thereupon, at the same instant when the solidification of the metal 2 begins, the metal 2 in the neighborhood 17 at the center of the part 6 is scooped out gradually with a suitable means. Then, the solidification progresses at a uniform rate from the part of the mold 15 in contact with the mold plane 16 thereof. At the point of the time when the wall thickness at which no shrinkage and cavities are generated in the solidified parts, the scooping up of the remaining metal 2 is ceased, and when the casting cools thoroughly, it is removed from the mold 15.