To prevent a fall accident and improve efficiency by providing a bucket on the extreme end of a driving arm of a working base rotating by driving crawlers by means of a hydraulic drive device, and arranging a winch on a supporting plate rotationally movably provided on a vehicle body.

When a work is executed at a height of the upper position of a surface of sloope 67 and the like, for preventing a fall accident due to collapse of earth and sand from generating, the work is executed while fitting the extreme end of a wire 21 to something. In this case, the wire 21 of a fall preventing winch 20 arranged on a supporting plate 18 is fitted to a tree or a wire fixing member 68 provided on the upper position of the surface of slope 67 and the like through a wire fair-leader 22. According to movement of a vehicle body 19, the supporting plate 18 is rotationally moved, and the wire 21 is extended or contracted by operating the fall preventing winch 20, and a driving arm is operated so as to execute the work.