The invention provides a combine harvester, excepting to be able to easily carry out maintenance work inside a grain tank and to preferably store harvested grains. The combine harvester has a grain tank (7) for storing the harvested grains in an internal storage space, and a side plate (50) in the grain tank (7) is configured to be able to switch between a storage state and a maintenance state. Inthe storage state, the storage space is closed and grains can be stored. In the maintenance state, the storage space is open to the external, and the storage space can be accessed. The grain tank (7)includes a side plate (50) and a tank main body portion (46), and is provided with a connecting device that connects the side plate (50) that is switched to the storage state with the tank main bodyportion (46). The connecting device includes a locking member (77) arranged on the side plate (50), and a frame body (58) arranged on in the tank main body portion (46) and locked by the locking member (77).