To remarkably improve throughput by efficiently working shear stress to a material to be crushed even if the material to be crushed is a soft and high toughness plastic or the like.

A rotary side crushing blade 16 of a rotary disk 10 and a fixed side crushing blade 29 of a fixed side disk 25 are respectively divided into a plurality of divided blades 17, 31 on the radial lines centering a driving shaft 8 and respective divided blades 17, 31 are each constituted of a plurality of small edges 19, 33. The rotary side small edge 19 and the fixed side edge 33 are inclined at a prescribed angle in the tangential direction of the rotation and have respectively opposed inclined direction. As a result, the sharpness of the edge faces of the rotary side and fixed side small edges 19 and 33 is effectively utilized, the shear stress of both small edges 19 and 33 regularly changes the direction to crush the material to be crushed from another direction, and then, the material to be crushed is efficiently crushed even if the material is the soft and high toughness plastic to improve the throughput.