This paper describes the elemental and phase composition, microstructure, and superconducting properties of Nb3Sn deposited by magnetron sputtering. The films were deposited on sapphire substrates using three different techniques: co-evaporation, layer-by-layer deposition of Nb and Sn, and sputtering of a stoichiometric Nb3Sn target. The influence of magnetron operation mode on the as-deposited film element composition is described. After high-temperature annealing at 700–900 °C, the results indicate the formation of superconductive films. The highest critical temperature of 16.9 K was obtained for the film deposited at a stoichiometric Nb3Sn target and annealed at a temperature of 800 °C for 12 h. These results could be used for superconducting radio-frequency applications.