To provide a scintillator, etc., capable of improving a light emission intensity.SOLUTION: A scintillator S comprises: a sapphire substrate 6; a GaN layer 4 which is provided at an incidence side with respect to the sapphire substrate 6 and contains GaN; a quantum well structure 3 which is provided at an incidence side with respect to the GaN layer 4; and a conductive layer 2 which is provided at an incidence side with respect to the quantum well structure 3. In the quantum well structure 3, a plurality of light-emitting layers 21 containing InGaN and a plurality of barrier layers 22 containing GaN are alternately laminated, and an oxygen-containing layer 23 containing oxygen is provided between the quantum well structure 3 and the conductive layer 2.SELECTED DRAWING: Figure 1