Abstract: An electric vehicle is provided with a swing arm one end of which is coupled to a swinging shaft and the other end of which supports a rear wheel. An electric motor is installed on the side of the other end of the swing arm and drives the rear wheel. The swing aim is provided with a housing space provided in the vicinity of the swinging shaft and a guide groove that positions the battery in the housing space, the battery is mounted inside the swing arm by fixing the battery positioned in the housing space via potting material. The housing space is provided with an opening for inserting the battery on the side of the electric vehicle and the battery is inserted and fixed into/to the housing space of the swing aim from the side of the electric vehicle.