The author determined the nitrate content in Misasa Hot-Springs, sampled from August to October, 1952, In all the well-waters, the amounts of nitrate were higher than 1mg/l, and the highest nitrate content was 9.6mg/l in the well-water in front of Mr. Aoki, s house. In the hot-springs, the author found 10 springs containing more than 1 mg/l of nitrate, and the highest nitrate content was 9.0 mg/l in the Hakuro-Yu, but the lotvest content was about 0 mg/l in the Iwasaki Hot-Springs. In Ishiyu and "Yamadaku-KyodoYu" during the stay of irrigation water in rice-fields from the rain season to September, the amounts of flow incrensed, but the content of radon and chloride decreased. On the other hand, in Hisui-no-yu, the chloride content decreased and the radon content increased with the amount of flow. Moreover, the amounts of nitrate were considerably high in the Ishiyu and Yamndaku-KyodoYu Hot Springs, but fairly low in the Hisui-no-Yu. So the author expects that some relation may be found between the variation of the radon content and the amounts of nitrate. The water samples, which nitrate contents were high, showed a tendency to have a high phosfate content generally.