RADIATION DETECTOR

A radiation detector includes a positioning member having a through hole through which radiation passes, a scintillator having an input surface to which the radiation passing through the through hole is input and configured to convert the radiation into scintillation light, a sensor unit having a light-receiving surface that receives the scintillation light converted by the scintillator and configured to detect the scintillation light, and a lens unit having a lens configured to perform image capturing on the input surface of the scintillator and the light-receiving surface of the sensor unit. The positioning member has a first positioning portion with which the input surface of the scintillator comes into contact to position the scintillator and a second positioning portion with which one end face of the lens unit comes into contact to position the lens unit.