The metal-to-insulator (MIT) characteristics of the multiphase vanadium oxide films including V2+, V3+, V4+ and V5+ ions prepared by reactive magnetron sputtering were studied. The average valency of vanadium ion increased when the residence time of active vanadium atom near the oxygen injection pipe, because the oxygen potential of this region is much higher than other part of chamber. Therefore, the final phases of the films depend on the configuration of sputtering system. For two phase films, resistivity changed by a factor of -103Ω·cm. However, MIT characteristics is getting weaker for the films consisting of more than two phases. Therefore, the strain sensitive phase transition is suggested as a mechanism of MIT of multiphase vanadium oxide thin films.