A drive wheel is intermediation driven by an additional element, while achieving a reduction in cost by making use of a plurality of existing motors. A drive motor as a drive source includes a plurality of motor bodies arranged coaxially with and adjacently to each other in the vehicle width direction to permit integral driving thereof, and is disposed forwardly of a pivot for a swing arm supporting the driving wheel. One end in the vehicle width direction of a drive shaft of the drive motor is made to be an output end for output to the driving wheel, and a drive sprocket for power transmission to the driving wheel is provided at the output end. The center of the drive motor in the vehicle width direction is disposed with an offset to the side opposite to the side of the drive sprocket with reference to the vehicle body center.