We have observed a drastic change in the properties of indium oxide (In2O3) thin films prepared by pulsed laser deposition in a pure helium (He) background gas on unheated glass substrates. At high He pressures above 1.0 Torr, transparent crystalline In2O3 films could be prepared, even though the deposition was carried out without the introduction of oxygen gas and substrate heating. At lower He pressures, blackish opaque films were deposited. These results can be accounted for by the inert background gas effects, which cause spatial confinement of the ablated species in the high-pressure and high-temperature region. Facilitated oxidation in this region would suppress oxygen deficiency in the deposited films.