Electronic states of Si(100)2×1 clean surface and Si(100)1×1-2H surface are studied with total current spectrometer. The occupied surface states are at 0.25, 8.4 and near 12 eV below thevalence band maximum, while the unoccupied surface states are at 0.7 eV above the valence band maximum. Two induced surface states of Si(100)1×1-2H are observed below the valence band maximum.