To easily from even a bending hole or a meandering hole, to simplify molding and to improve the quality of a casting by using a tube formed by winding a wire in a spiral-state as a core, at the time of producing the casting having tubular hole in the inner part.

The tube formed by winding the wire 3 in the spiral state is formed in a prescribed shape matching the necessary hole diameter, and set in a mold 1 as the core, and a mold is formed, and the molten metal is poured to make the casting 2. After solidifying, one end of the casting 2 forming the spiral tube is pulled out of the hole opening part of the casting 2 and removed to obtain the casting having a desired inner hole. Since the core formed by winding this wire in the spiral state can freely be bent, this core can easily be formed into the bending or the meandering shape, and further, since gas is not generated even at the time of pouring the molten metal, the gas venting in the mold is unnecessary and then, such problem as development of defective casting caused by the generated gas is dissolved. Then, the material and the diameter of the wire are suitably decided based on the characteristic of the casting to be produced, and the recessed part between the wires wound spirally may be coated with an incombustible material.