An investigation of surface electromigration of Cu overlayer on Si (111) was done by using scanning Auger electron spectroscopy. A Cu patch with a thickness of several monolayers was evaporated at room temperature on a cleaned Si (111) -7 × 7 substrate. The initial application of dc current through the substrate gave rise to an ordered Cu layer with approximately 2 monolayers, on the top of which three dimensional islands were grown. Then, directional spread of the ordered Cu layer toward the cathode occurred. This mass-transport, however, was suddenly terminated and, coincidently, the Cu Auger signal began to reduce in intensity. The tiansport process was discussed in terms of the Stranski-Krastanov growth and the intermixed interface.