An object is to reduce the cost of a screw (20) and improve the quality of molded products. A rear end of the screw (20) is connected to a drive apparatus. The screw includes a screw head, a reverse-flow prevention apparatus, and a plasticizing member disposed rearward of the reverse-flow prevention apparatus. The plasticizing member includes a screw body (52), a flight (53) projectingly formed on an outer circumferential surface of the screw body (52), and a pressure member (54) formed to extend over a predetermined distance from the front end of the screw body (52) and to be located adjacent to the reverse-flow prevention apparatus. The pressure member (54) has a flat outer circumferential surface. Since the pressure member (54) has a flat outer circumferential surface having a diameter equal to or greater than the diameter of the screw body (52), the shape of the screw (20) can be simplified, and the cost of the screw (20) can be lowered. In addition, the number of locations where a molding material stagnates can be reduced.