It has been desired to improve the durability of a quality measuring device while facilitating the maintenance work inside a grain tank. Further, it has been desired to improve the durability of a quality measuring device while making it possible to suppress a rise in the temperature of the quality measuring device without sacrificing the storage capacity of a grape tank. The present invention is provided with a grain tank (7) for storing harvested grains, and a quality measuring device for grain quality measurement is provided at a position near the outer side in the width direction of the machine in the grain tank (7), and a side plate (50) on the side of the outer peripheral portion of the grain tank (7) on which the quality measuring device is installed is convertible between a retention state in which the retention space in the tank is closed to enable retention of the grains and a maintenance state in which the storage space is opened to the outside to enable access to the storage space. In addition, a quality measuring device for grain quality measurement is provided in a side end portion in the grain tank storing the harvested grains and an introduction port (96) for introducing air for cooling the quality measuring device and an outlet for discharging the air after cooling the quality measuring device are provided on the side wall portion on the side of the outer peripheral portion of the grain tank on which the quality measuring device is installed, and installed along the side wall portion are an introducing vent path (98) for communication and connection between the quality measuring device in the storage case (23) and the introduction port (96) and a discharge vent path for communication and connection between the discharge port and the quality measuring device.곡립 탱크의 내부의 유지보수 작업을 용이하게 행할 수 있도록 함과 함께, 품질 계측 장치의 내구성의 향상을 도모할 것이 요망되고 있었다. 또한, 곡립 탱크의 저류 용량을 희생시키지 않고, 품질 계측 장치의 온도 상승을 억제하는 것을 가능하게 하면서도, 품질 계측 장치의 내구성의 향상을 도모할 것이 요망되고 있었다.수확한 곡립을 저류하는 곡립
