To realize a small-sized lightweight crushing apparatus while keeping the crushing ability and to reduce the load during crushing.

The crushing apparatus 1 for plaster boards is equipped with a single rotation axis 11 horizontally disposed in a crushing chamber 9 in a casing 7 having an input opening 3 and a discharge port 5, and with a plurality of fan plates 13 to 22 extended in the radial direction from the rotation axis 11 and formed at a prescribed interval or proper intervals in the axial direction. The plurality of plates 13 to 22 include a first plate group 13 to 17 and a second plate group 18 to 22 having a prescribed phase difference from that of the first plate group 13 to 17. Each plate 13 to 22 has a blade 23 to 32 with an arc face formed as protruded outward at the top end of the plate.