To carry out the arrangement of a clawler and its operater suitable to all the works and the ambient conditions such as the extending and the contraction of the boom and the arm of a backhoe and a crawler crane; the rotation of 360° scope of the equipments including an operater's seat; the correction of the unballance of a car body resulting from the fluctuation and the shock of a machine body; the securing of the conditions of a paddy field, the ground and the like, the running property and the maneuverability in a working space and the like, freely by the operation in the operator's seat.

Two crawlers 3 at the front side, and two crawlers 4 at the rear side, are provided at the lower part of a car body, and while the front side crawlers 3 each other, and the rear side crawlers 4 each other are made possible to regulate the interval in the width direction through reciprocating engines 5 and 6, the reciprocating engines 5 and 6 are made possible to set the rotation at a desired angle through a separate reciprocating engine 9 at the operator's seat, and furthermore, the front side crawlers 3 and the rear side crawlers 4 are made possible to regulate the interval relatively through reciprocating engines 7 and 8 which are operated in the operator's seat.