To provide solidification technology of natural soil to prevent it from generation of molds and bacteria, elution of its component caused by rainwater, etc., and cracking caused by swelling and shrinkage of moisture.

This solidification soil is made by adding a clay, an ash and an aromatic resin to the natural soil and mixing them in a mixer. By using this technology, as moisture does not permeate into the natural soil, generation of the bacteria and saprophytes is prevented and discoloration of the soil is avoidable.