The aim of this study was to develop a new method for determination of inorganic cations and anions in hot spring water with capillary electrophoresis and indirect UV detection. Separations were performed with fused-silica capillary (92cm (80cm to the detector) × 50μm I.D.). Sodium, magnesium, potassium, calcium, lithium and barium as cation sample, and fluoride, chloride, bromide, nitrate, sulfate and phosphate as anions were examined. Background electrolyte solution for cations was solution containing copper (II) acetate and ethylenediamine, and background electrolyte solution for anions was solution of benzoic acid, Tris, and hexadecyltrimethylammoniumhydroxide. Concentrations, pH of background electrolyte solution and capillary temperature, applied voltage, and so on were examined. Electropherograms were obtained by means of indirect UV detection at 220nm. Separation of six cations and six anions were achieved. The detection limits for cations and anions ranged from 0.12 to 1.6ppm. The relative standard deviations (RSDs) of migration times ranged from 0.10 to 1.3%, and the RSDs of peak areas ranged from 0.99 to 2.5%. This method was applied to determine these species in different samples of hot spring water at city of Kobe in Japan. This study was reported at MSB 2006 (20th International Symposium on Microscale Bioseparations)