The influence of alloying element S, Se or Te on the oxidation resistance of pure Cu was studied by oxidizing in 0.1 MPa pure oxygen atmosphere at 573-873 K in comparison with a 6N Cu (99.9999 wt.%). The addition of S, Se or Te is found to improve the oxidation resistance of Cu remarkably. This improvement is contributed from the accumulation of alloying element at the Cu2O/Cu interface and segregation of alloying elements at grain boundaries in Cu2O.