We have investigated the transitions that take place at high-temperature from the oxidized state to the 7×7 phase on the Si (111) surface using high-temperature (HT) scanning tunneling microscopy (STM). The oxidized surface was transformed at 580 °C after oxidation by exposing the surface to 45 L of oxygen at 480° C The structural modification was directly observed by HT-STM. The corner adatom was created at the initial stage of the reconstruction, and then the disordered, 5×5 and 7×7 phases successively appeared on the surface. By etching Si atoms, the island structure was formed on the surface because of the reduced Si density. Finally, the completed 7×7 terrace was created.