Abstract: An all-direction-changing mechanism and a driving power transmission mechanism combined together comprising a plurality of connecting rods radially extending from a connecting center, direction-changing cranks on the outer ends of the connecting rod controlling the direction of wheels mounted on the cranks, the ends of the connecting rods being connected with said direction-changing cranks by direction-changing crank pins, the connecting center being a center crank fastened to a steering mechanism mounted on a revolving vehicle body so that when the steering wheel is turned around for changing the vehicle's running direction, the connecting rods are also moved in parallel to one another, and as a result the vehicle body and all the wheels also change direction in the same angle.