A radiochemical analysis of sea water containing fission materials collected near Bikini Atoll in June,1954, was performed. The sea water was boiled with hydrochloric acid, iron and lanthanum salts (each 5 mg as Fe and La) were added to it. They were precipitated as hydroxide, which was dissolved in hydrochloric acid and ferric chloride was extracted with ethyl ether. The remaining solution was evaporated to dryness and the residue was dissolved in hydrochloric acid. Using the latter solution the group separation was done with cation exchanger resins. To the filtrate separated from hydroxide precipitate, ammonium oxalate was added to produce the oxalate of alkaline earths. Strontium was separated by the use of fuming nitric acid. Analytical result shows the presence of Y-91, Ce-141,144, Ru-103,106, Rh-106, Zr-95 (Nb-95) and Sr-89 in which the most part was fractions of Y and Ce.