In this study, the photoluminescence and radioluminescence properties of MnO-doped SnO-ZnO-P2O5 glasses are examined. We have confirmed that linear dose-dependence and radioluminescence emission decay depend on Mn2+ concentration. Energy transfer from donor Sn2+ center to acceptor Mn2+ center is observed in both photoluminescence and radioluminescence processes, and the energy transfer efficiency is more than 90% when the Mn2+/Sn2+ ratio is 5. Since emission intensity of Mn2+ is higher than that of Sn2+ in radioluminescence compared to photoluminescence, it is suggested that energy transfer from the host matrix to Mn2+ center by X-ray occurred preferentially over energy transfer to Sn2+ center. The present results suggest that the conventional parity rule for photoluminescence is not always adaptable for radioluminescence, although emission-related energy levels are the same for both the processes.