A conventional combine harvester of the invention is provided with a traveling machine body 1 which mounts an engine 7 serving as a power source, a reaping device 3 which has a reaping blade 15, and a threshing device 9 which has a threshing cylinder 21. The engine 7 is arranged in one side of a rear portion of the threshing device 9 in the traveling machine body 1, and a radiator 172 for water cooling the engine and a cooling fan 170 for air cooling the engine 7 and the radiator 172 are arranged in a front side of the engine 7. A cooling air path of the engine 7 is formed by a cover duct body 173 which covers an area from the other side in an opposite side to the threshing device 9 in the engine 7 to a front side of the radiator 172 and the cooling fan 170.
