PURPOSE: To produce easily a single part constituted of plural materials by casting by providing successively and continuously molten metals of plural materials.

CONSTITUTION: A required material of the material corresponding to a zone 5 is first cast through a sprue 1 according to the specifications of a product to manufacture the product consisting of, for example, two kinds of materials. When the material to form the other part except said part is thereafter cast into the mold, the materials are in the molten state and are therefore mixed with each other, thereby forming a zone 6. The material poured afterward flows into said zone to form a zone 7. The casting product of the single part satisfying precisely the specifications required for each part of the product is thus obtd.