Abstract: A method for manufacturing a molded product, which has a highly homogeneous thin film, at low cost by operating an injection molding machine and a film forming device at a high rate of operation is provided. A molded product formed by an injection molding machine is conveyed to a temporary stage by a first conveying device. The molded products corresponding to several times of an injection molding step are pooled on the temporary stage by the repetition of an injection molding step. A second conveying device collectively conveys all the molded products, which are pooled on the temporary stage, to a film forming device. Films are formed on the molded products by the film forming device, and the molded products are conveyed to the outside by a third conveying device. The injection molding step is continuously performed while a film forming step is performed.