Chemical state analysis using X-ray photoelectron spectroscopy was performed on high quality tin-doped indium oxide (ITO) films prepared by pulsed laser deposition. Changes in Sn 3d(5/2) spectra associated with the carrier electron generation from Sn dopants were first observed: the crystalline ITO film with higher carrier electron density showed higher binding energy, larger peak width, and larger asymmetry than the amorphous film with lower carrier density. The binding energy shift is attributed not to a change in valence of Sn but rather to a change in the oxygen coordination of the Sn dopant. Lower binding energy and smaller peak width in the 10 atom % doped film compared with the 5 atom % doped film were explained from an increase in the inactive Sn content in terms of the carrier generation caused by the formation of Sn complexes.