PROBLEM TO BE SOLVED: To smoothly discharge a threshed stalk with long stalk length, etc., from a stalk discharging port.SOLUTION: Each of a front wall and a rear wall 56 constituting a threshing chamber 20 includes a shaft supporting member 59 to rotatably support the axis of a threshing cylinder 21. The threshing cylinder 21 is extended back and forth between the front wall and the rear wall 56 in a manner to place the rear end of the threshing cylinder 21 close to the rear wall 56. A stalk discharging port 23 is opened at a lower rear part of the threshing chamber 20. The rear wall 56 is formed in a manner that an area Aa positioned outside of an ascending rotation path Ka of tip ends of threshing teeth 46 when ascending a plurality of threshing teeth 46 protruding from the threshing cylinder 21 and below the rotary center P2 of the threshing cylinder 21 is set as a bulged area A bulged backward in the whole wall area of at least the rear wall 56 to form a backward bulged portion 56A without the bottom in which the bulged area A bulges backward from the rear wall 56, and that the area Ac provided with the shaft supporting member 59 is positioned at a front side of the bulged area A in at least the whole wall area and close to the rear end of the threshing cylinder 21.COPYRIGHT: (C)2013,JPO&INPIT【課題】稈長の長い脱粒穀稈などの排稈口からの排出を円滑に行えるようにする。【解決手段】扱室20を形成する前壁体及び後壁体56のそれぞれに扱胴21の中心軸を回転可能に支持する軸支部材59を備えて、扱胴21を、扱胴21の後端が後壁体56に近接するように前壁体と後壁体56とにわたって前後向きに架設し、扱室20の後下部に排稈口23を形成し、少なくとも後壁体56の全壁面領域のうちの扱胴21に突設した複数の扱歯46が上昇移動する際に扱歯46の先端が描く上昇回転軌跡Kaの外側で扱胴21の回転中心P2よりも下側に位置する領域Aaを後向きに張り出させる張出領域Aに設定して、後壁体56に張出領域Aを後向きに張り出させた無底の後向き張出部56Aを形成し、かつ、少なくとも全壁面領域のうちの軸支部材59を配備する領域Acが張出領域Aよりも前側に位置して扱胴21の後端に近接するように後壁体56を形成してある。【選択図】図5