A novel resin organized from an amidoxime derivative of chitosan is prepared and the adsorption characteristics of metal ions are examined. Metal ions are adsorbed by forming chelates coordinated by nitrogen atoms of primary amino groups and oxygen atoms of oxime groups. The amidoxime chitosan resin (AO-b-1) retards the adsorption of nickel ion compared with that on N-(sulfopropyl)chitosan (PSC), and the maximum adsorption capacity of copper ion on AO-b-1 is 1.6 times as much as that for PSC, The adsorption capacity of copper ion is further enhanced by alkali treatment of the resin, The amidoxime chitosan resin prepared here is found to be an excellent adsorbent with high adsorption capacity and selectivity for copper ions.