A novel chitosan-supported sulfonic acid resin modified by propane sultone was prepared and the adsorption characteristics of metal ions are examined by using a crosslinked chitosan-supported sulfonic acid resin (PSC) and a crosslinked chitosan resin (CLC). In the low acidity region, the metal selectivity of PSC is similar to that of CLC. This suggested that the selectivity of PSC was attributed not to sulfonate group but to the chitosan matrix. The role of the sulfonate is believed to be enriching the metal concentration in the neighborhood of the chitosan matrix. At the same time, since the hydrogen ions is also enriched in a thin layer near the surface of the resin, the characteristic adsorption curves of PSC shift to the high pH region compared with those of CLC. The adsorption equilibrium constants of metal ion on PSC and CLC are evaluated. The maximum adsorption capacity for PSC in the case of adsorption of copper is 1.6 times that of CLC. On the other hand, in the high acidity region, the maximum adsorption capacity for PSC in the case of adsorption of palladium is lower than that for CLC because of steric hindrance.