We report a highly selective adsorbent for Cu(II) prepared using the metal-imprinted technique. As the base material, we used the natural adsorbent chitosan, which can be obtained from chitin by the deacetylation reaction. Chitosan was modified with ketoglutaric acid to introduce multiple functional carboxyl groups, which interact with metal cations. Cu(II)-imprinted chitosan was prepared by the imprinting technique and its behavior as an adsorbent for various metal ions, including Cu(II), Ni(II), Co(II), Zn(II), and Cd(II), was investigated. Cu(II)-imprinted chitosan exhibited extremely high selectivity for the imprinted Cu(II) ion compared with the other metal ions. This result indicates that the metal imprinting technique is very useful for the development of highly selective adsorbents. However, desorption of Cu(II) from the imprinted adsorbent was not sufficient because of the strong binding between Cu(II) and the imprinted adsorption sites.