Combine harvester

The invention relates to a combine harvester, which is expected to eliminate useless space and increase grain storage capacity in a grain tank as much as possible. The grain tank (7) is provided with a side plate (22) and a tank main body part (23) other than the side plate (22), an opening (26) from the upper part to the lower part and from the front part to the rear part of the grain tank (7) is formed in a side wall part (21) of the tank main body part (23), and the side plate (22) is configured to be capable of switching between a closed state in which the opening (26) is closed and an open state in which the opening is opened by swinging. The side plate (22) is provided with a protruding part (30) protruding from the inner side surface of the side plate (22) toward the inner side of the box main body part (23) in a shape along the shape of the opening (26), and when the side plate (22) is switched to the closed state, the protruding part (30) is in a state along the inner peripheral edge of the opening (