A subject-to-be-examined support unit that supports a subject to be examined, a light source unit that outputs light entering the subject-to-be-examined support unit from a side opposite to a side by which a sample is supported, a fluorescent plate that is illuminated with the light that has been output from the light source unit and passed through the subject-to-be-examined support unit and the sample, and emits fluorescence, a photomultiplier that detects fluorescence that has been emitted from the fluorescent plate and passed through the subject-to-be-examined support unit and the sample, and a plate support unit that supports the fluorescent plate are provided. The plate support unit is structured in such a manner that a distance between the subject-to-be-examined support unit and the fluorescent plate is changeable by moving the fluorescent plate in a direction closer to the subject-to-be-examined support unit and in a direction away therefrom.