To evaluate the performance of a new water circulating system (rate of evaporation, 40 kg/h) in a washing process for radiation-contaminated soil, decontamination by water washing and water circulating tests of the system were conducted in Fukushima with soil contaminated with over 570,000 Bq/kg of radioactivity. The results were as follows. (1) Condensation water with low contamination and low content of impurities was produced by the water-circulating machine, and the recovery rate of water from filtrate was 86-88%. (2) The concentrated solution contained 77-100% of fission products in soil washing water together with impurities.