Mn-doped γ-Ga2O3 thin films with a defective spinel structure have been epitaxially grown on spinel (100) substrates using pulsed laser deposition. The crystal quality of the films is strongly dependent on preparation conditions, particularly substrate temperature and laser energy density, as well as Mn concentration. In the 7 cation% Mn-doped film grown under the optimized conditions, the full width at half maximum in the x-ray diffraction rocking curve for the (400) plane is 117 arcsec and the root-mean-square roughness of the surface is approximately 0.4 nm. These values are comparable to those of the spinel substrate. The film shows a uniform tetragonal distortion with a tetragonality of 1.05.