To enable continuous surplus soil treatment in the field by a soil treatment vehicle which is simple in structure and easy in treatment operation, obviates the need for the ground leveling, etc., of the installation site, moves after the movement of a digging point even in a digging site where the digging point moves without restriction of a place to be installed.

A soil treatment apparatus 4 is mounted on the pallet of a vehicle to be constituted. The soil treatment apparatus 4 is equipped with a soil hopper 5 for receiving soil to be treated, the first conveyer 1 for transporting the soil in the hopper 5 to a rotary kiln 6, a treatment agent hopper 7 for receiving a treatment agent to be supplied to the soil, the rotary kiln 6 for forming treated soil by mixing the soil to be treated with a treatment agent, a trommel 8 for selecting the treated soil discharged from the rotary kiln 6 into large sized grains and small-sized grains, a crashing machine 11 for crashing the treated soil of large-sized grains, and a selector 12 for selecting the treated soil discharged from the crashing machine 11 into the crashed treated soil and the uncrashed treated soil.