PURPOSE: To enable forming without deformation by simultaneously executing the solidification in respective parts while keeping the thick part and the thin part of a molded product at the uniform temp.

CONSTITUTION: A fixing mold 1, movable mold 2 and core pin 3 for forming the thick part 4a of the molded product 4 are made of the material having large heat conductivity, and a nesting 6 forming the thin part 4b is made of the material having small heat conductivity. The whole body is cooled while uniformly keeping the whole body temp. by delaying the cooling rate in the thin part and simultaneously solidified to prevent the deformation.