Qualitative and quantitative analysis of sinter deposits in a distributing pipe used for seventeen years (Sample No.1) and adhere to bathtub wall for eleven years (Sample No.2 and Sample No.3) in Misasa radioactive hot springs
were investigated. The results were as follows ; (1) The color of deposits of Sample No.1 and Sample No.2 was black and the color of deposits of Sample No.3 was white. The metal elements in these deposits were qualitative analysed by spectraspan plasma emission spectrophotometry (SPES) and by fluorescent X-ray spectrometry. Following elements were detected, in Sample No.1 : Na, Mg, Al, K, Ca, Mn, Fe, Cu, As, Sr, Ba, Mo, and Pb, in Sample No.2 : Na, Mg, Al, Si, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Sr, Ba, Pb and Cl and in Sample No.3 : Na, Mg, Al, Si, K, Ca, Mn, Fe, Cu, Zn, As, Rb, Sr, Mo, Ba, S, and Cl, (2) The metal elements in these deposits were quantitative analysed by SPES, atomic absorption spectrophotometry and emission spectrophometry. Following elements were determined, in Sample No.1 ; Mn : 411.6, Fe : 65.7, Ba : 20.0, Ca : 11.9, Na : 5.7, Cu : 4.5, K : 4.2, Sr : 2.9, Zn : 2.6, Mg : 1.4, in Sample No.2 ; Mn : 248.2, Fe : 28.5, Ba : 15.6, Ca : 25.0, Mg : 10.5, Na : 9.3, Cu : 5.4, K : 4.9, Sr: 7.4, Zn : 3.3, and in Sample No.3 ; Ca : 275.2, Sr : 32.4, Mg: 12.4, Na: 18.7, K: 5.0, Mn: 1.7 and Fe: 0.6mg per gram. The main components of these deposits were manganese compounds (Sample No.1 and Sample No.2) and calcium compounds (Sample No.3). Qualitative and quantitative analysis of barium in sinter deposits of Misasa spa was done by authers for the first time. (3) Radioactivity in these deposits were observed by autoradiography. Among the radioactive elements, concentration of radium were 3.41×10(-8) Ci/g (Sample No.1), 4.70×10(-9) Ci/g (Sample No.2) anp 2.36×10(-11) Ci/g (Sample No.3), respectively.