The oxidation of carbon monoxide was carried out on the copper zeolites prepared by ion exchange and impregnation. Hydrogen mordenite(HM), partially dealuminated mordenite(HM#) obtained by repeating thermal treatment as well as ammonium ion-exchange and HY were ion-exchanged in cupric nitrate solution to get the copper zeolites having various level of copper content. HY, HM#, and HZSM-5 were impregnated with copper or platinum in 1wt% and the activities of these impregnated catalysts were compared with those of ion-exchanged ones. The activities of ion-exchanged catalysts for the oxidation of carbon monoxide increased with an increase in the copper containing level of the catalysts, but decreased with an increase in the valence state of the copper[i.e., Cu(0)>Cu(I)>Cu(II). It is considered that the activity of ion-exchanged catalysts is affected by the sillica-alumina ratio of the zeolite structure. Par-tially dealuminated copper mordenite showed highest activity among the catalysts. The impregnated catalyst was more active than the ion-exchanged one at the same level of copper content. The activity of impregnated catalyst was more active than the ion-exchanged one at the same level of copper content. The activity of impregnated catalysts also in-creased as their silica-alumina ratio of the structure increased as the same as the ino-exchanged catalysts. The higher activity for Cu(0) could be also explained by the increase of copper concentration on the surface of zeolite.