PROBLEM TO BE SOLVED: To dispose an existing huge amount of soil and radioactive waste contaminated by radioactive substances in a state that radiation is sealed and structure a social resource by using it.SOLUTION: An underground continuous wall body 32 is formed in such a manner that it has a closed shape in a plane view surrounding a land within a prescribed range. Or underground continuous wall bodies are formed so as to face each other on both sides of the land within the prescribed range. An impermeable layer 34 is formed inside of the underground continuous wall body or between the underground continuous wall bodies facing each other. A contaminated soil molded block 1 made by adding a solidifying material into soil, sludge after sewage treatment or waste-incinerated ash, contaminated by radioactive substances, and molding it into blocks, or a contaminated soil contained block 24 made by containing and sealing the soil, sludge or incinerated ash in a concrete box body is plurally arranged on the imperm
