Provided is a radiation detector 1 capable of improving reliability while using a plurality of light receiving elements to provide a large screen size. A radiation detector 1 includes: a flexible supporting substrate 5 that includes a radiation incident surface 5a and a radiation emission surface 5b a scintillator layer 6 made from a plurality of columnar crystals H formed on the emission surface 5b through crystal growth and generating light due to the incident radiation a moisture-proof protective layer 7 covering the scintillator layer 6 and filled between the plurality of columnar crystals H and light receiving elements 8A to 8D arranged to oppose the scintillator layer 6 and detecting the light generated in the scintillator layer 6.