PURPOSE: To smoothly treat invaded foreign matter by fixing upper edge of vertical elastic introducing board at upper edge part of outlet and freely suspending lower edge of the board.

CONSTITUTION: A suction fan 24 and a space 34 are installed in upper part position of second thrower 17 and winnowing room 7 side of the space 34 is closed with choking side board 35. Vertical outlet 36 is formed at lower part of the choking side board 35 and upper edge of vertical elastic introducing board 37 is fixed at upper edge part of the outlet 36, then lower edge of the board 37 is freely suspended to construct a dust-discharging device in a thresher. Foreign matter invaded into the space 34 is introduced to lower part with sliding on upper wall of the second thrower 17 as winnowing room 7 side is closed and discharged through the outlet 36 to outside as vertical outlet 36 at lower part of the choking side board 35. Besides, the invaded foreign matter is smoothly treated because of introducing to inlet 21 of the second thrower 17 by the vertical elastic introducing board 37 fixed at upper edge part of the outlet 36.