A radiation detector includes a substrate having a plurality of charge collection electrodes, a radiation absorption layer disposed on one side with respect to the substrate and formed of a perovskite material, a voltage application electrode disposed on the one side with respect to the radiation absorption layer, a bias voltage being applied to the voltage application electrode so that a potential difference is generated between the voltage application electrode and each of the plurality of charge collection electrodes, and a protective member disposed on the one side with respect to the substrate and being in contact with at least portions opposite to each other in a side surface of the radiation absorption layer.