The observation of the intensity of solar ultra-violet radiation was carried out on the roof ,as well as in the field of the meteorological observatory of the Kyushu Imperial University, during the pericd August 1st 1932 to August 31st 1933, as one of the programs adopted by the committee for the second polar year, observation in Japan. To measure ultr a -violet radiation, two methods were used. (1) Hill's method :-5.8 cc solution of pure methylene-blue is added to 3o cc of pure acetone and made up to I oo cc with distilled water. With this solution, a small silica tube with the inner diameter 3 mm and length 5 cm is filled to the brim. The tube is exposed to sunlight for 30 minutes and then the decolorization was measured by the colorimeter, comparing with the series of ten differently decolorised solutions. The decolorization is made by exposing the normal solution to the mercury lamp, each differing by 5 minutes. Table I is the outcome of the measurement on each International Day i. e. Thursday. (2) The method of the photoelectric cell :?T o record the d aily variation of the ultra-violet radiation continuously, the sodium photoelectric cell was used. The solar ray was filtered by a nickel glass which passes only the rays 2910-4000A. The solar ray reflected on the silvered uviol glass attached to a heliostat placed on the roof of the building enters into the cell which is electrically connected with the galvanometer and its mirror makes the point image on the bromide paper on the revolivng drum. Table II is prepared by measuring the area of the record-strip of the bromide paper. As clearly shown in the tables, th e maximum intensity reaches usually at 12 h 30 min. and the month of maximum intensity and that of minimum are respectively August and January. The time and month of the maximum intensity occur usually therefore at those of highest temperature in Japan.