PURPOSE: To shorten a construction period and to reduce construction cost without requiring a removal of surplus soil forming a crushed stone and crushed stone dust layer and an asphalt concrete layer on the upper layer of a soil cement layer having soil generated in the field as a skeleton material.

CONSTITUTION: A soil setting agent is added to a levelled ground 1, drilled and agitated, then, a rule 6 laid at a constant interval to the finished surface is used to level a mixed soil by a level rod 7, press by a roller and form a road bed 2. Then, crushed stone, crushed stone dust and soil produced in the field are mixed, a soil setting agent is added and kneaded and the obtained product is laid, leveled to the rule face, pressed by the roller to form a bed 3. Before the road bed 2 and the bed are cured, lumps of crushed stone 4 are dispersed, pressed by the roller, a part thereof is bitten to unify the road bed 2 and the bed 3. Further, the thin layer made of asphalt concrete is formed on the finished face of the bed 3.