The role of adatoms in Surface Enhanced Raman Scattering(SERS) system with copper electrode was studied for 0.1M KBr aqueous solution and 0.1M KC1 aqueous solution. The adatomic effect on SERS and surface reflectance was confirmed from the potential dependance of SERS intensity and surface reflectivity during Oxidation-Reduction Cycle (ORC). In the case of nondiffusive regime of adatoms, the irreversible loss of SERS was not observed and the surface reflectivity was almost at a constant value. But, in the case of diffusive regime of adatoms, we observed the irreversible loss of SERS and simultaneous increase of surface reflectivity. On the copper electrode, Cu adatoms diffused away in aqueous SERS solution above 40℃ and also at 20℃ without pyridine.