An analogy of solvent extraction to ion-exchange was taken to explain anion affinities to anion-exchangers. Distributions of the model compound whose cation was the ionogenic group of an anion-exchanger and whose anion the counter ion, between water and an organic solvent, were investigated. The degree of distribution of the model compound for a solvent layer was expected to increase with increasing anion affinities to the corresponding anion-exchanger. Cobalticinium, benziltrimetylammonium and benzildimethylamine salts were employed as model compounds for the polymeric olygomethylene cobalticinium anion-exchanger, the strong base anion-exchange resin and the weak base anion-exchange resin, respectively. The distribution sequences in solvent extraction were essentially identical with the ion affinity series in anion-exchange. From these correlations, the selectivity coefficient for an anion was explained as the affinity of an anion to an ionogenic group with the use of an ion-pair concept. Some differences between ion-exchanges and solvent extractions were discussed.