To provide a dust box, that can be easily and strongly assembled by a single person without using a jig or the like.

A back plate 5 and a front plate 6 are erected on a rear end edge and a front end edge of a bottom plate 2 through engagement recesses and engagement projections. A right and a left side plates 3 and 4 are erected on a right and a left end edges of the bottom plate 2 through engagement recesses and engagement projections. A right and a left end parts of the back plate and a right and a left end parts of the front plate 6 are held by a pair of holding parts 31 and 41 in the right and the left side plates 3 and 4, and the right and the left side plates 3 and 4 are fixed to the bottom plate 2 through connecting bolts and nuts. A rear cover 71 of a cover plate 7 is fixed to the right and the left side plates 3 and 4 through self-tapping screws, while it is fixed to the right and the left side plates 3 and 4 through a pipe member disposed on its back surface.