An axle structure is provided with an axle housing for internally passing an axle shaft having wheels connected to both left and right ends thereof, and a drive motor unit. The axle housing includes a large diameter housing center portion having a recessed portion which is recessed from an opening portion on a front surface side toward a rear surface side, and small diameter hollow shaft portions connected as a left and right pair to both sides of the housing center portion. The drive motor unit is fitted into the recessed portion and is bolted to the axle housing by means of tightening bolts.