PURPOSE: To efficiently crush chestnuts between drums of both sides by providing an inner side crushing sieve drum by inscribing to an outer side crushing sieve drum or partially being in close vicinity thereto and providing a driving mechanism for rotating and driving these inner and outer crushing sieve drums.

CONSTITUTION: When cut chestnuts W are supplied to voids V between both the sieve drum 5, 7 from a charging port in a state where the outer and the inner crushing sieve drums 5, 7 are rotated by driving of a motor 9, the chestnuts W are crushed by a crushing action at an inscribing part T of the both drums 5, 7 and by difference of peripheral speeds. The crushed nuts Wa are shifted through sieve holes respectively to an outside of the outer crushing sieve drum 5 and to an inside of the inner crushing sieve drum 7 and shells Wb of the nuts together with a part of the nuts Wa are sent out to a space between both the drums 5, 7. Then, nuts Wa shifted to the outside of the outer crushing sieve drum 5 are dropped directly into a receiving dish 32 and nuts Wa shifted to the inside of the inner crushing sieve drum 7 are introduced on a screen plate 31 from an opening of the drum 7 and stored in the receiving dish 32. The shells are stored in a receiving dish 34.