The invention provides a combined harvester capable of inexpensively carrying out natural and reverse rotation driving of a harvesting part with simple structure. A transmission tank (36) is provided in front side of an advancing machine body of a threshing device (5), the transmission tank (36) is equipped with a tank input shaft (37) transferring driving force from an engine (20) and threshing drum output shafts (38) in front and back directions of the advancing machine body; the threshing drum output shafts (38) is linked with the tank input shaft via a conical gear mechanism (43) to transfer the driving force of the tank input shaft (37) to a threshing drum (5a). A harvesting output shaft (39) is linked with the tank input shaft (37) via the conical gear mechanism (43) in a manner of being driven in a rotating direction opposite to the rotating direction of the tank input shaft (37), and the harvesting output shaft is equipped in the transmission tank (36). The invention is equipped with a natural rotation clutch (40) and a reverse rotation clutch (41).