Abstract: Waste plastics including solid plastics, thin plastics, and foamy plastics are fed into a ring die of an extrusion molding machine. The waste plastics are either semi-melted or melted, and are then extruded onto an outer circumferential surface the ring die through die cavities. Thus, granular plastic moldings are extruded onto the outer circumferential surface of the ring die through the die cavities, and are then cut or scraped from the outer circumferential surface of the ring die. The pellets have a melt-solidified surface, and have a strength sufficient to reach a predetermine zone in a raceway of a furnace and a grain diameter sufficient to be fed at a velocity higher than a limiting velocity thereof during injection to the furnace.