To enable a vehicle to perform efficient rotational drive with no axle shaft required, by providing a reduction gear mechanism in the vicinity of a running drive wheel to drive it.

From a case housing 17 covering a first end reduction gear mechanism 12 provided in a central position under a machine body respectively to right/left sideward, a shaft case 18 is protruded in each output side opening end 18a thereof, a coupling case 20 formed by a hollow cylinder unit is fit mounted in coaxial shape, a drive carrier 22 internally mounting a planet gear 21 is internally fitted in this case, and a second end reduction gear mechanism 23 is formed, and a right/left running drive wheel is respectively directly mounted in the drive carrier 22.