PURPOSE: To constrain a thermal strain by uniformly cooling indirectly, to prevent the coarsening of a thick metal part and to make a ferrous casting product in good quality by forcibly cooling the thick metal part of a ferrous casting product cast in a lost wax mold from the external part of the mold.

CONSTITUTION: In the case of casting a ferrous casting product, especially the casting product of non-tempered casting steel and spherical graphite cast iron into a lost wax mold 1, the mold external part of the thick end part 2a having larger thickness of a connecting rod casting part 2, for instance, is forcibly cooled by the mist projection from a nozzle 8a. Since the thick metal part is cooled indirectly the cooling is uniformized, the generation of thermal strain is prevented and in the case of non-tempered casting steel the coarsening of ferrite is prevented to make the hardness and strength sufficient, and in the case of a spherical graphite cast iron the reduction in the fatigue strength due to the coarsening of the spherical graphite is prevented. Consequently the quality of the casting product is improved.