Electrical properties of the sol-gel derived amorphous films containing P2O5 have been investigated. In the binary system of P2O5-SiO2, the surface resistivities at 25°C under a relative humidity ranging from 50 to 90% RH were 2-3 orders of magnitude higher than that of the P2O5-TiO2 films. In a nominal composition of P2O5⋅9SiO2 (molar ratio), the conductivity at 25°C of the film prepared by using H3PO4 for the starting materials of P was 10-6S⋅cm-1. This was 1 or 2 orders of magnitude higher than that of the films prepared by using partially hydrolyzed P2O5: PO[OCH(CH3)2]3-x(OH)x or PO(OCH3)3 as starting materials of P, respectively. In the former case of PO[OCH(CH3)2]3-x(OH)x, however, the conductivity of the film obtained from a coating solution kept for 40d after preparation increased up to 10-6S⋅cm-1. In these films, we observed absorption band at 1300cm-1, which was assigned to P=O stretching vibration. The high proton-conductivities come from the increase of hydrogen-bonded protons in the glass structure with increasing the P=O bonding content.