A chassis has a structure in which a front structure and a rear structure are linked by an upper floor and a lower floor. The front structure is linked to a front wheel via a coupling member, a front wheel support member and a shaft. The front structure has a cylindrical support member. In addition, the rear structure is linked to a rear wheel via a shaft. A reinforcing member, which links the front structure and the rear structure in the central part of a space for accommodating a battery, is installed inside the space for accommodating the battery. The front end of the reinforcing member is linked to the cylindrical support member in the front structure. The upper surface of the reinforcing member is fixed to the upper floor and the lower surface of the reinforcing member is fixed to the lower floor.