To obtain an apparatus capable of separating radioactive cesium 137, released due to the nuclear crisis at Fukushima Daiichi Nuclear Power Station caused by the Great East Japan Earthquake, from soil without producing compounds.

Polluted soil containing radioactive cesium 137 is put into a water tank to be stirred, and then is made to precipitate in water. The temperature of the water tank is raised to 28.44°C, which is a melting point of metal cesium, or more to melt the radioactive cesium 137 to change its shape from a thin rod-like shape to a ball-like shape. Accordingly, its precipitation speeds become slow so that the radioactive cesium floats in water for a longer time than other substances such as sand having heavy specific gravities to be separated from these substances. Likewise, by using an electric magnet, cesium oxide-shaped radioactive cesium 137 is separated from slowly precipitating soil matter by being attracted to the electric magnet. After recovering of the soil matter and stopping of electric power supply to the electric magnet, the radioactive cesium attracted to the electric magnet is allowed to fall and precipitate. A container into which the radioactive cesium is recovered is reheated to melt and connect the radioactive cesium to make a solid of pure radioactive cesium after cooling at normal temperature. Thus, complete separation and recovery from soil or ash can be performed by this apparatus.