To provide eluent for liquid chromatography for rapidly and precisely analyzing a divalent cation without losing the separation of a monovalent cation when simultaneously analyzing monovalent and divalent cations in ion chromatography, and to provide an ion chromatography analysis method using the eluent.

In the ion chromatography analysis method, the eluent containing a compound that contains at least two phosphoric acid bases in the same molecule is used instead of a well-known method for increasing the concentration of additives such as pyridine -2, 6- dicarboxylic acid. By using the eluent, the divalent cations can be rapidly and precisely analyzed without losing the separation of the monovalent cation when simultaneously analyzing the monovalent and divalent cations in the ion chromatography.