[en] Chemical complexities of ruthenium in nitric acid solution cause difficulties in removing this element from waste solution arising from reprocessing of spent nuclear fuel. The waste solution from the ⁹⁹Mo production process by means of ²³⁵U(n,f)⁹⁹Mo reaction has similar chemical composition to that of spent nuclear fuel reprocessing. Chemical species and their relative abundance are supposed to be quite similar in the both waste solutions. Various ruthenium species in the waste solution arising from ⁹⁹Mo production process were separated by high performance liquid chromatography for the both high level (VH-1) and medium level (MH-1) aqueous waste solutions. Up to fifty species of ruthenium were separated by cation exchange chromatography with nitric acid. It is confirmed by the cation exchange behaviors that most of these species are anionic and neutral ones. The transformation of chemical species of ruthenium and their relative abundance are determined after each waste treatment. The effectiveness of charcoal-zinc column treatment is ascribed to that the column removes not only positively charged ruthenium species but also negatively charged ruthenium species and neutral ruthenium species from slightly acidic solution. (author)