PURPOSE: To obtain a low-cost, lightweight dump truck by providing in a place to discharge earth a body lifting device which oscillates up and down the body of the dump truck into standing and collpased positions by means of expansion and contraction of each hydraulic cylinder to thereby discharge earth and sand, etc., in the body.

CONSTITUTION: A stopper 5 and a body lifting device 6 are installed in a predetermined place A to discharge earth from a hopper, etc. To carry out the work of discharging earth from a dump truck, a pair of front and rear auxiliary hydraulic cylinders 14 are each contracted so that a main hydraulic cylinder 11 collapses sideways. Under such conditions the dump truck is retreated to the place A to discharge earth and the rear wheels 7 of the truck are stopped by a stopper 5 and positioned and each auxiliary hydraulic cylinder 14 is expanded and the main hydraulic cylinder 11 is put in its vertical position so that a pin receiver 13 is opposite to a pin 4. Next each auxiliary hydraulic cylinder 14 is allowed to freely expand and contract by external forces and the main hydraulic cylinder 11 is expanded and the body 2 is oscillated upward with the pin receiver 13 engaged with the pin 4, so that earth and sand, etc., are discharged into the place A to discharge earth.