PURPOSE: To simply separate and purify uranium isotopes by feeding a uranium isotope-containing solution to an annular chromatography while injecting an eluant to an anion exchange resin in the continuously rotating annular chromatography.

CONSTITUTION: A solution containing the uranium isotopes 1 to be separated and a suitable eluant 2 are fed to an anion exchange resin bed in a continuously rotating annular chromatography 3 so that a uranium 235 isotope fraction is separated from a uranium 238 isotope fraction and an impurity fraction 4. Ammonium hydroxide 5 is added to the respective fractions to precipitate them as their ammonium diuranates (ADUs) 6, 7, respectively. Uranium oxide rich in uranium 235 is produced by calcining the ADU precipitated from the uranium 235 fraction in a calcinator 8 and uranium oxide rich in uranium 238 is produced by calcining the ADU precipitated from the uranium 238 fraction in a calcinator 9.