PURPOSE: To suppress the generation of a hold-up volume peak in the specimen component separated from a liquid mixture, by using the liquid mixture consisting of a pure solvent and an eluate.

CONSTITUTION: The pure solvent through a valve 14 from a pure solvent container 10 and the eluate from an eluate container 18 are mixed in a mixing apparatus 16. The specimen solution is from a sampling coil 22 is also supplied to said apparatus 16 and the liquid mixture containing the specimen solution from the apparatus 16 passes a separation column 24. In this case, the specimen is separated by the affinity with the packing agent of the column 24 and elution is successively performed from an anion having poor affinity to carry out analysis through a detector 26. By this constitution using the liquid mixture, the generation of a hold-up peak in the specimen component as found in a case using only the eluate is suppressed and the minute amount analysis of different specimens can be simultaneously performed without changing a separation column for each specimen.