To provide a cylindrical column structure in which ion-exchange resins are sealed in a cylindrical column, and the difficulty of passing a solvent through the resins due to the increase in the flow resistance of a solvent by the expansion of the resins and the lowering of column efficiency due to gaps produced among resin particles by the contraction of the resins are prevented.

A pair of filters 10 and 12 is arranged in the cylindrical column 2 to hold the ion-exchange resins 8 between them. At least one filter is set slidably along the inner surface of the cylindrical column. The volume of a space filled with the ion-exchange resins is increased with the expansion of the resins and decreased with the contraction of the resins.