To immobilize heavy metals such as Cd and Pb in soil and to surely prevent these heavy metals from elusion from the soil by spraying a phosphate aqueous solution or a Ca compound and the phosphate aqueous solution to the soil contaminated with the heavy metals.

In the case that the soil contaminated with the heavy metals such as Cd and/or Pb is treated, a range of the soil contaminated with the heavy metals and a concentration distribution are researched and the phosphate aqueous solution or the phosphate aqueous solution and the Ca compound are sprayed so that one equivalent or more phosphates and one and half equivalents or more Ca compounds against the heavy metals enable to come into contact with the heavy metals. As a spraying method, in the case that the contamination due to the heavy metals is only against the soil near the earth surface, the phosphate aqueous solution, etc., are directly sprayed on the earth surface, while the phosphate aqueous liquid, etc., are sprayed from the dug holes dug at several places to the contamination parts, in the case that the contamination reaches a deep part in the earth.