PURPOSE: To obtain a selecting part structure of a thresher capable of showing the optimum selecting performance according to a treating condition.

CONSTITUTION: A selecting part structure of a thresher is equipped with a front selecting part 8 longitudinally composed of a grain pan 13 to receive dropped materials falling through a receiving net 4 of a threshing chamber 2 and a grain sieve 17 for dropping and selecting the dropped material selected by the grain pan 13 by specific gravity in a first material recovery part 12 and with a rear selecting part 9 for selecting a material dropped from a dust sending port 5 at the rear of the threshing chamber 2 and is furnished with a first driving mechanism A to reciprocate the front selecting part 8 approximately along a dropping and selecting face of the grain sieve 17 and a first driving mechanism B for rocking the rear selecting part eccentrically and vertically in such a way that the inclination of the grain pan 13 from the dropping and selecting face of the grain sieve 17 can be varied.