PURPOSE: To always sterilize and clean sand by spraying water containing a heavy metal ion having sterilizing power into a sandbox in park, etc., every prescribed time.

CONSTITUTION: An ion generator 4 is installed in a flowing water passage 3 from a water supply source to a sandbox 2. A valve 7 in the flowing water passage 3 is opened by a switch-opening and closing mechanism 6 and simultaneously, the ion generator 4 is started by electric power from an electric source part 5. A metal ion is subjected to electrolysis in the ion generator 4 and water containing the metal ion is sprayed onto sand by a water-spraying apparatus 8. The sprayed water is passed through space between sands and deeply permeated into sand without being limited to the surface of sand to sterilize the whole sand.