It was found that the chelating resins (RNH) containing amidoxime groups show the selective adsorption ability for uranium in sea water. The favorable chelating resins were prepared by the reaction of macroreticular acryronitrile-divinylbenzene copolymer beads with hydroxylamine in methanol. When sea water (104 times as large as the resin volume) was passed through the RNH column at the space velocity of 60 hr-1, 80% of uranium on that in sea water was recovered. The elutton of uranium adsorbed on RNH was accomplished by passing 1 N sulfuric acid solution through it. The recycle of adsorption and elution was found to be satisfactory. © 1979, The Chemical Society of Japan. All rights reserved.