Since the battery is placed in the battery tray, the battery can stably held in place even if the battery support part of the floor panel is somewhat uneven. The battery support part (31) on which the battery (B) is supported is a part of a floor panel (30) of the vehicle (21), the number of the mounting holes (31) is at least two, the battery is placed in a battery tray (5) placed on the battery support part, the battery tray has lugs (5a) provided with holes (5b) having a diameter greater than that of the hook rods (1) and smaller than an outside diameter of the tubular spacers (3) at positions corresponding to the mounting holes, and the battery tray (5) is fastened together with the battery (B) to the battery support part (31) of the floor panel through the tubular spacers by the hook rods.