A vehicle in which an output of a motor is transmitted to an axle through a reduction mechanism in order to rotate a wheel, wherein: the axle passing through the wheel and substantially coaxially connected to the wheel is a hollow cylindrical shaft; the motor has a motor shaft inserted into a hollow portion of the cylindrical shaft substantially coaxially with the cylindrical shaft so as to extend from both ends of the cylindrical shaft; on one side of the wheel, the motor is connected to a base end of the motor shaft extending from one end of the cylindrical shaft; on the other side of the wheel, the reduction mechanism is connected to a leading end of the motor shaft extending from the other end of the cylindrical shaft; and the reduction mechanism rotates the cylindrical shaft in accordance with rotation of the motor shaft caused by driving of the motor; characterized in that the vehicle is an electric vehicle, and in that the electric vehicle further comprises: a double-sided swing arm for supporting the motor shaft, the cylindrical shaft, and the wheel by supporting the motor on the one side of the wheel and the reduction mechanism on the other side of the wheel; a motor module composed of the motor and a motor case for storing the motor, the motor module being removable from the swing arm and the wheel: and a reduction mechanism module composed of the reduction mechanism and a reduction mechanism case for storing the reduction mechanism, the reduction mechanism module being removable from the swing arm and the wheel. the axle passing through the wheel and substantially coaxially connected to the wheel is a hollow cylindrical shaft; the motor has a motor shaft inserted into a hollow portion of the cylindrical shaft substantially coaxially with the cylindrical shaft so as to extend from both ends of the cylindrical shaft; on one side of the wheel, the motor is connected to a base end of the motor shaft extending from one end of the cylindrical shaft; on the other side of the wheel, the reduction mechanism is connected to a leading end of the motor shaft extending from the other end of the cylindrical shaft; and the reduction mechanism rotates the cylindrical shaft in accordance with rotation of the motor shaft caused by driving of the motor; characterized in that the vehicle is an electric vehicle, and in that the electric vehicle further comprises: a double-sided swing arm for supporting the motor shaft, the cylindrical shaft, and the wheel by supporting the motor on the one side of the wheel and the reduction mechanism on the other side of the wheel; a motor module composed of the motor and a motor case for storing the motor, the motor module being removable from the swing arm and the wheel: and a reduction mechanism module composed of the reduction mechanism and a reduction mechanism case for storing the reduction mechanism, the reduction mechanism module being removable from the swing arm and the wheel. a double-sided swing arm for supporting the motor shaft, the cylindrical shaft, and the wheel by supporting the motor on the one side of the wheel and the reduction mechanism on the other side of the wheel; a motor module composed of the motor and a motor case for storing the motor, the motor module being removable from the swing arm and the wheel: and a reduction mechanism module composed of the reduction mechanism and a reduction mechanism case for storing the reduction mechanism, the reduction mechanism module being removable from the swing arm and the wheel.