Abstract: An object is to prevent internal stress from remaining in a molded product to thereby improve the quality of the molded product. A mold apparatus (10) includes a first plate and a second plate which is disposed to face the first plate and is made of the same material as that of the first plate. At least one of the first and second plates has voids formed in its surface facing the other plate. Since at least one of the first and second plates has a plurality of voids formed in its surface facing the other plate, a molding material present in a cavity can be prevented from suffering local temperature unevenness. The pattern of a cavity insert can be satisfactorily transferred to a molded product to thereby improve the quality of the molded product. Since the first and second plates are made of the same material, diffusion bonding can be easily conducted. Furthermore, since the first and second plates have the same coefficient of thermal expansion, the mold apparatus (10) can have improved durability.