A dump truck includes a plurality of rear wheels (15) rotatably attached to a frame (11) and two GPS receivers (101, 102) arranged to be dislocated from each other in an anteroposterior direction of a vehicle. Any point selected from an area C, in the vehicle coordinates system B set in the dump truck, where the rear wheels contact a ground is defined as a reference point D. The two GPS receivers are arranged so that a vertical line descends from a line segment PQ, connecting two points P, Q of which positions are calculated by the two GPS receivers, to the reference point D. This makes it possible to accurately estimate an attitude of mining machinery by two position estimation means without stopping operation of the machinery.