Energetic negative ions and neutral atoms were simultaneously observed using a time-of-flight apparatus during indium-tin oxide (ITO) film preparation by conventional planar mapetron sputtering of an ITO target. The sputtering was performed in pure Ar gas and compared with ZnO : Al sputtering. Energetic particles such as O- and O2- ions and neutral O atoms were detected in the time-of-flight spectra, although the flux intensity of these particles was much less than that found in the ZnO sputtering. It was also found that other particles exist at the same time, which were thought to be reflected Ar atoms or O3- ions from the target surface. However, the flux intensity of these particles was found to be less than that of the energetic O- ions and O atoms. The strong energetic particles, which primarily bombarded the substrate during the ITO sputtering were found to be energetic 0- ions and 0 atoms.