Radiation Detector

A radiation detector includes a plurality of radiation detecting devices (semiconductor devices) having a plane of incidence where coming radial rays enter. The radiation detecting devices are arranged in a manner that the planes of incidence are arranged side by side substantially without any space therebetween, when the planes of incidence are viewed from a direction along which radial rays come. The plurality of radiation detecting devices are arranged in a manner that heights in a normal direction of the planes of incidence of the plurality of radiation detecting devices differ from heights in a normal direction of the planes of incidence of respective adjacent other radiation detecting devices.