Abstract: An object of the present invention is to provide a metal mold of a simple structure that can be used for injection molding a combined product composed of some molded pieces regardless of the accuracy and the shape of a desired combined product and a method of molding such combined product. A metal mold M for injection molding comprises a first piece mold 5 for molding a first molded piece 2, a second piece mold 4 for molding a second molded piece 6, and a pin core 8 for forming an insertion hole 1. A method of injection molding a combined product P comprises the steps of injection molding the first molded piece 2 from a first plastic resin A, removing the pin core 8 that is used for forming the insertion hole 1 in the first molded piece 2 in the former step from the first molded piece 2, and injection molding the second molded piece 4 from a second plastic resin B.