PURPOSE: To obtain a thresher responsive to more rows or a higher speed of a combine harvester without increasing the size of a machine body by improving the threshing treatment performance.

CONSTITUTION: The thresher is obtained by arranging a treating drum 17 for retreating materials untreated in a threshing chamber 3 in a lapping state with a threshing drum 4 in the grain culm transferring direction and in a state thereof, rotated and driven around the shaft center parallel to the shaft center of the threshing drum 4 at a position of the ear tip side on the downstream side in the grain culm transferring direction of the threshing drum 4, plural treating drums 18 and 19 rotating in the same direction around the shaft center parallel to that of the treating drum 17 side by side at positions the downstream side of the grain culm transferring direction of the threshing drum 4 and on the conveyed plant foot side of the conveyed grain culms of the treating drum 17, stretching a receiving net along the lower side of the respective treating drums 17, 18 and 19, setting the rotational direction so as to treat the materials to be treated while transferring the materials to the plant foot side of the conveyed grain culms by cooperation with the receiving net and leaking the treated materials down to a downward grading part.