A radiation detector that allows accurate discrimination of generating positions of fluorescence in a height direction generated in scintillation counter crystals. Specifically, the radiation detector includes scintillation counter crystals whose faces are rough surfaces. This allows suppression of unexpected partial reflection of fluorescence between adjacent scintillation counter crystals, leading to ideal spread of the fluorescence generated in a scintillator. Consequently, a radiation detector that allows accurate discrimination of the generating positions of fluorescence is provided.