Abstract: An object of the present invention is to provide a method for producing a polymeric molded product, which does not undergo a considerable molecular weight reduction during melt-molding, even in a polymer may easily lose its molecular weight when it is in a melted state. The present invention provides a method for producing a polymeric molded product, which comprises melt-molding a polymer comprising lamellar crystals that are different in lamella thickness, in a temperature range where some of the lamellar crystals undergo melting and flowing, and the other balance lamellar crystals remain unmelted.

Abstract: An object of the present invention is to provide a method for producing a polymeric molded product, the method enabling expansion of a temperature range that can be used for partial melting. The present invention provides a method for producing a polymeric molded product, which comprises subjecting a crystalline polyhydroxyalkanoate to a heating treatment at a temperature equal to or higher than a glass transition temperature; and melt-molding a polyhydroxyalkanoate yielded by the heating treatment, which comprises lamellar crystals that are different in lamellar thickness, in a temperature range where some of the lamellar crystals undergo melting and flowing, and the other balance lamellar crystals remain unmelted.