PURPOSE: To enable to climb up the foot part of a stairway by a vehicle itself, by making a center height of a driving wheel larger than that of a stair.

CONSTITUTION: As a height (h') of the center O of driving wheels 5, 5' is larger than that (h) of a stair in climbing up a stairway, it is possible to make climbing at the foot part 51' of the stairway by a vehicle itself even if an auxiliary tilting stand is not used. Although the vehicle is overturned when a line of action of the center of gravity G of a cargo 51 lies at a position (a), the vehicle can be prevented from overturning, in this case, by moving the center of gravity G to a position G' through movement of a skid 52. In addition to the above, as right and left running devices 9, 9' can be turned and driven independently by right and left driving mechanisms respectively, straight travelling, turning and spin turning can be done easily.