To realize substantial and apparent stability, structural strength, and compactness by making the end part distant from a pivot part of a platform vertically rockable through the pivot part on the side closer to one longitudinal end of a traveling device into a mechanism having a horizontal part raised and lowered to the traveling device.

In a flat ground part, both the slide device 14 and jack 15 of a horizontal mechanism 3 are laid in non-operated state, and a platform part 4 is lowered to a traveling device 2, and set horizontally. In going up a stairway or slope, a pivot part 32 is set forward, and the slide device 14 and jack 15 of the horizontal mechanism are extended by the operation of a worker according to the inclination of the traveling device 2, respectively, to set the platform part 4 horizontal. In going down the stairway or slope, the traveling device 2 is traveled with the pivot part 32 backward. Consequently, the lower fulcrum part for supporting the platform part 4 is positioned to the center-of-gravity position on the traveling device, whereby not only substantial strength stability but also apparent stability can be provided, and the compactness is also realized by lowering the platform part 4.