A notched region in which the outer periphery of a screw flight is cut out is provided in a molding material feed screw. A wedge-shaped portion is formed by both a front wall surface of the screw flight and a wall surface of the boundary where the outer periphery of the screw flight is cut out. As a result of rotation of the molding material feed screw, since the wedge-shaped portion advances while pushing aside resin pellets located in the front thereof in two lateral directions of the front wall surface of the screw flight and the wall surface of the boundary where the outer diameter of the screw flight is cut out, entrapment of the resin pellets between the edge of a material supply port of a molding material supply device and the outer periphery of the screw flight is avoided as much as possible.