The study results of optical properties of amorphous nanosized TiO2:Ag composite films with the structure of an amorphous TiO2 matrix with inclusions of isolated Ag nanoparticles are presented. The TiO2:Ag films were obtained by ion-plasma high-frequency magnetron co-sputtering of a polycrystalline TiO2 and Ag target. The films were 40–50 nm thick, and the maximum silver concentration reached 9.0 at.%. The fundamental absorption band edge was analyzed for different possible absorption laws. It is shown that, in TiO2 and TiO2:Ag films, the edge of the fundamental absorption band is formed mainly due to indirect allowed optical transitions (the quadratic absorption law), and this absorption law does not change with increasing silver concentration. The optical bandgap in TiO2:Ag films depends on the Ag concentration and is determined by the degree of order in the amorphous matrix.