The four wheel vehicle uses an electric motor (142) for driving the vehicle and a battery unit (160) for supplying electric power to the electric motor. The lower chassis (5) of the vehicle includes a pair of front side frames (10) extending linearly in a fore and aft direction with an upward slant and a progressively increasing lateral mutual spacing from a front part thereof to a rear part thereof, a pair of rear side frames (12) connected to rear ends of the respective front side frames, and extending linearly in a fore and aft direction with an upward slant from a front part thereof to a rear part thereof in continuation of the corresponding front side frames in a mutually parallel relationship, and a plurality of cross members (14, 16, 18, 20, 22) connecting the side frames to each other.