A co-rotating intermeshing type twin-screw extruder comprising: first and second screws (14a, 14b) for a co-rotating intermeshing type twin-screw extruder (12, 13), the first and second screws (14a, 14b) having an outer circumferential surface on which a groove is spirally formed, wherein the first and second screws (14a, 14b) are configured to rotate about an axis center of each screw in a state where the first and second screws (14a, 14b) mesh with each other and to transport raw material in a predetermined direction along the axis center, and wherein an inner surface of the groove of each of the first and second screws (14a, 14b) comprises: a first surface, which faces in the predetermined direction; and a second surface, which faces in a direction opposite to the predetermined direction, wherein the first surface of the first screw is formed such that the outer circumferential surface of the second screw coincides with the first surface of the first screw without a gap therebetween in a state where the first and second screws (14a, 14b) mesh with each other, and wherein the first surface of the second screw is formed such that the outer circumferential surface of the first screw coincides with the first surface of the second screw without a gap therebetween in a state where the first and second screws (14a, 14b) mesh with each other, characterized in that a gap is formed between the second surface of the first screw and the outer circumferential surface of the second screw in a state where the first and second screws (14a, 14b) mesh with each other, and a gap is formed between the second surface of the second screw and the outer circumferential surface of the first screw in a state where the first and second screws (14a, 14b) mesh with each other. first and second screws (14a, 14b) for a co-rotating intermeshing type twin-screw extruder (12, 13), the first and second screws (14a, 14b) having an outer circumferential surface on which a groove is spirally formed, wherein the first and second screws (14a, 14b) are configured to rotate about an axis center of each screw in a state where the first and second screws (14a, 14b) mesh with each other and to transport raw material in a predetermined direction along the axis center, and wherein an inner surface of the groove of each of the first and second screws (14a, 14b) comprises: a first surface, which faces in the predetermined direction; and a second surface, which faces in a direction opposite to the predetermined direction, a first surface, which faces in the predetermined direction; and a second surface, which faces in a direction opposite to the predetermined direction, wherein the first surface of the first screw is formed such that the outer circumferential surface of the second screw coincides with the first surface of the first screw without a gap therebetween in a state where the first and second screws (14a, 14b) mesh with each other, and wherein the first surface of the second screw is formed such that the outer circumferential surface of the first screw coincides with the first surface of the second screw without a gap therebetween in a state where the first and second screws (14a, 14b) mesh with each other, characterized in that a gap is formed between the second surface of the first screw and the outer circumferential surface of the second screw in a state where the first and second screws (14a, 14b) mesh with each other, and a gap is formed between the second surface of the second screw and the outer circumferential surface of the first screw in a state where the first and second screws (14a, 14b) mesh with each other.