To control the posture of a drilling member charged on a mast so as to turn to the perpendicular direction of the gravity even on an inclined ground.

This working vehicle is equipped with traveling devices 15, 17 and a motor 3 driving a hydraulic pump and provided with an extensible mast 33 at the front side of the machine body and the mast is equipped with a drilling member 50. The mast 33 is rotatably supported at the front part of the machine body. A hydraulic cylinder is arranged between the middle of the mast and the machine body 1 to widely tilt the mast from the vertical position to the position inclined to the forward or backward direction. In this way, the posture of the drilling machine 50 equipped on the mast 33 can be controlled so as to turn the perpendicular direction of the gravity.