A multi-shaft kneading machine comprising: a cylinder that includes grooves on an inner wall thereof; at least two screws that extend in the cylinder in parallel with each other wherein each screw can be rotated around an axis of rotation; and a pair of gate rods that sandwich said at least two screws and that are opposite to each other, wherein each gate rod can be rotated on the grooves of the cylinder around an axis of rotation, the axes of rotation of the gate rods being orthogonal to the axes of rotation of the screws, wherein each gate rod (5a, 5b) has at least two recess parts, and the recess parts that are opposite to each other form respective spaces through which said at least two screws penetrate; and each gate rod (5a, 5b) includes: two intermediate parts that include the recess parts respectively and three wall parts that are located to alternate with the two intermediate parts and the intermediate parts of the pair of gate rods (5a, 5b) are opposite to each other and the wall parts of the pair of gate rods (5a, 5b) are opposite to each other, and each wall part has a large diameter part that is fitted into the groove of the cylinder, characterized in that each intermediate part includes a first contact surface, each wall part includes a small diameter part having a radius of curvature that is equal half a distance between the axes of rotation of the gate rods (5a, 5b) and that is smaller than the radius of curvature of the large diameter part, each gate rod (5a, 5b) can be rotated to a minimum-degree-of-opening position where the first contact surface comes into surface contact with the screw and where an area of a channel that is formed between the gate rods (5a, 5b) and the screw is minimized and the small diameter parts of the pair of gate rods (5a, 5b) are in contact with each other. a cylinder that includes grooves on an inner wall thereof; at least two screws that extend in the cylinder in parallel with each other wherein each screw can be rotated around an axis of rotation; and a pair of gate rods that sandwich said at least two screws and that are opposite to each other, wherein each gate rod can be rotated on the grooves of the cylinder around an axis of rotation, the axes of rotation of the gate rods being orthogonal to the axes of rotation of the screws, wherein each gate rod (5a, 5b) has at least two recess parts, and the recess parts that are opposite to each other form respective spaces through which said at least two screws penetrate; and each gate rod (5a, 5b) includes: two intermediate parts that include the recess parts respectively and three wall parts that are located to alternate with the two intermediate parts and the intermediate parts of the pair of gate rods (5a, 5b) are opposite to each other and the wall parts of the pair of gate rods (5a, 5b) are opposite to each other, and each wall part has a large diameter part that is fitted into the groove of the cylinder, characterized in that each intermediate part includes a first contact surface, each wall part includes a small diameter part having a radius of curvature that is equal half a distance between the axes of rotation of the gate rods (5a, 5b) and that is smaller than the radius of curvature of the large diameter part, each gate rod (5a, 5b) can be rotated to a minimum-degree-of-opening position where the first contact surface comes into surface contact with the screw and where an area of a channel that is formed between the gate rods (5a, 5b) and the screw is minimized and the small diameter parts of the pair of gate rods (5a, 5b) are in contact with each other.