Mixing performance of resin material in the rotational direction of the screw is enhanced. Kneading disc 7 is fitted onto rotatable shaft 3 and is arranged in cylinder 2. Outer circumferential surface 8 of kneading disc 7 of the present invention that faces cylinder 2 has band portion 9 that extends between both ends 7a, 7b of kneading disc 7 in axial direction X of shaft 3 and that forms a minimum gap with cylinder 2. Band portion 9 includes at least one bent part 10.