To provide a waste crusher capable of reliably preventing the generation of noise, vibration, and powder dust when crushing wastes and thereby preventing adverse effects on ambient environments.

The waste crusher comprises a funnel-like hopper 6, a coarsely crushing mechanism 3 for coarsely crushing a prescribed amount of wastes in the hopper 6 and dropping the crushed wastes from a lower end port; a finely crushing mechanism 4 for finely crushing the coarsely crushed wastes which are dropped through the lower end port, a sieving member 12 installed in the lower side of the finely crushing mechanism 4 and having a large number of holes 12a with a prescribed diameter or smaller, a storage box 16 for storing wastes S with a prescribed diameter or smaller passed through the holes 12a of the sieving member 12, an outer air-shutting box 17 having a waste throwing inlet 17a and a discharge outlet 17b and capable of housing the hopper, the coarsely crushing mechanism, the finely crushing mechanism, the sieving member, and the storage box in the inside and shutting them from the outer air, and opening or closing doors 22 and 23 for opening or closing the throwing inlet 17a and discharge outlet 17b, respectively.