Cathodoluminescence, photoluminescence, and photoluminescence excitation spectra of ZnGa2O4:Cr thin films were investigated. Sublinear lux-ampere cathodoluminescence characteristics were obtained at current densities 0.001–8 mA/cm2. Bands in luminescence spectra were interpreted and their relation to the film production conditions was determined. It was found that the local crystal-field strength in the films increased after annealing in argon although the increase was less than that of films annealed in air.