The Mn-doped copper nitride (Cu3N) films with Mn concentration of 2.0 at. % have high crystallinity and uniform surface morphology. We found that the as-synthesized Mn-doped Cu3N films show suitable optical absorption in the visible region and the band gap is similar to 1.48 eV. A simple photodetector based on Mn doped Cu3N films was firstly fabricated via magnetron sputtering method. The fabricated device with doping of Mn demonstrated high photocurrent response and fast response shorter than 0.1 s both for rise and decay time superior to the pure Cu3N. Furthermore, the energy levels of Mn-doped Cu3N matched well with ITO and Ag electrode. The excellent photoelectric properties reflect a good balance between sensitivities and response rate. Our investigation reveals the excellent potential of Mn-doped Cu3N films for application of photodetectors.