The present invention relates to a combine harvester. The invention settles a problem of harvest loss caused by the discharging of grains ON a swinging sorting shelf to the outside of a threshing device and the precision and efficiency of the threshing operation are increased. ON a first dust discharging opening (21) which is equipped to the back left side part of a dust discharging processing chamber (18), a first discharging guiding plate (29) which is provided with a first inclined surface (29a) that guides the dust material discharged from a first dust opening (21) to the right back flow for falling to the surface of farmland. ON a second dust discharging opening (23) which is equipped to the back right side part of the dust discharging processing chamber (18), a second discharging guiding plate (24) which is provided with a second inclined surface (24a) that guides the dust material discharged from the second dust discharging opening (23) to the right back flow for falling to the surface of the farmland and a third inclined surface (24b) that guides the dust material discharged from the second dust discharging opening (23) to the right back flow of the threshing device (4) for falling to the surface of the farmland is provided.
