PURPOSE: To crush rapidly without contamination by placing a rod-shaped polycrystal silicon in a microwave for a short time, and heating rapidly the rod- shaped polycrystal from inward by dielectric heating.

CONSTITUTION: The microwave is oscillated by an oscillator 1, and introduced into a directional coupler 2 through a waveguide. The microwave whose travelling wave M1 and reflected wave M2 are measured by the directional coupler 2 is introduced into an oven 6 through a matching device 3. Meanwhile, a rod- shaped polycrystal silicon 5 is inserted into the oven 6 from the upper part of the oven 6. The rod-shaped polycrystal silicon 5 is dielectrically heated rapidly from inward by the microwave, and the crushed silicon 10 is obtained. The crushed silicon 10 is dropped into a vessel 7 filled with demineralized water 8, washed, and then stored in a storage vessel 11 through a conveyor 9.