PURPOSE: To reduce the necessary amount of replenishing water by achieving the efficient desalting of sand by a small amount of washing water by bringing and having sat adhered thereto into continuous counterflow contact with washing water to perform desalting and applying desalting treatment to washing water increased in salt concn. to reuse said washing water.

CONSTITUTION: Sand having salt adhered thereto is fed through a belt conveyor 1 and a bucket conveyor 2 while washing water is allowed to fall on the sand in each bucket 3 from a nozzle 15 to be brought into continuous counterflow contact with the sand to wash the sand. Subsequently, the washing water increased in salt concn. is stored in a receiving tank 7 to be sent to a reverse osmosis desalting apparatus 6 through a filter device 9 and a cartridge filter 13 to be desalted and regenerated. At this time, tap water 5 is supplied in an amount almost equal to the amount of the conc. water 16 discharged by the apparatus 6 to be again utilized as washing water. As a result, sand can be efficiently desalted by a small amount of washing water and the necessary amount of replenishing water at the time of reuse is reduced.