PURPOSE: To reduce fourth loss and to raise rigidity of a rear wall plate of a treating chamber.

CONSTITUTION: A plural barrel type threshing device is equipped with a threshing barrel 2 for threshing grain culms which are held in a threshing chamber 3 and fed while transporting in the shaft direction, with a treating barrel 9 which is arranged side by side at one end of the threshing chamber and treats the threshed material received by a treating chamber 8 while transporting backward and with a crossing flow fan 15 which is laid at a position behind the threshing barrel and the treating barrel in the direction perpendicular to these barrels and sucks and discharge dust. The treating barrel 9 is extended long backward from the end of the threshing chamber 3 and a rear wall plate 13 of the treating chamber 8 supporting the end part of the treating chamber is connected to the front of a casing 16 of the crossing flow fan 15 and supported.