XPS or AES sputter depth profiling sometimes encounters difficulties with the materials that are damaged by ion bombardment. Therefore, it becomes difficult to determine precise chemical states of such materials. The damages of oxides by ion bombardment as observed in XPS spectra were reviewed. Spectrum changes are classified into three types; (1) additional peaks appear as a result of reduction for one type of the oxides, (2) the spectra are broadened for the second one, and (3) the third type oxides are not chemically changed. It is pointed out that these changes are related to the change of the enthalpy of atomization and ionicity. Secondly, the intensity changes as a function of sputtering time is formulated using reduction cross sections by the ion bombardment and sputtering yield.