Structural control of In 2 Se 3 polycrystalline thin films was attempted by molecular beam epitaxy (MBE) technique. In 2 Se 3 polycrystalline films were obtained on glass substrates at substrate temperatures above 400°C. VI/III ratio greatly affected crystal structure of In 2 Se 3 polycrystalline films. Mixtures of α-In 2 Se 3 and γ-In 2 Se 3 were obtained at VI/III ratios greater than 20, and layered InSe polycrystalline films were formed at VI/III ratios below 1. γ-In 2 Se 3 polycrystalline thin films without α-phase were successfully deposited with VI/III ratios in a range of 2 to 4. Photocurrent spectra of the γ-In 2 Se 3 polycrystalline films showed an abrupt increase at approximately 1.9 eV, which almost corresponds with the reported bandgap of γ-In 2 Se 3 . Dark conductivity and photoconductivity measured under solar simulator light (AM 1.5, 100 mW/cm 2 ) were approximately 10 -9 and 10 -5 S/cm in the γ-In 2 Se 3 polycrystalline thin films, respectively.