We have studied valence electron-state changes of Si during initial oxidation of Si(111) clean surface, HF-treated Si(001) and Si(lll) surfaces by Anger valence electron spectroscopy (AVES). The results showed that the valence electron-state changes during initial oxidation were sensitively reflected in Si[2s.2p,V] (V = 3s,3p) AVES spectra and that they depended on both initial surface treatment and surface orientation. The local valence electron-states, local density of states in other words, showed the characteristic-structure evolution depending on the initial surface treatment and surface orientation.