Charged Particle Beam Device

Provided is a charged particle beam device that can impart a function of an energy filter to even a small BSE detector. The charged particle beam device includes a fluorescent substance that converts charged particles generated by irradiation of a sample with a charged particle beam into light; a detector that detects the light emitted from the fluorescent substance; a light guide element for guiding the light from the fluorescent substance to the detector; a light amount adjuster that adjusts the amount of light that is received by the detector through the fluorescent substance and the light guide element; and a control unit that controls the light amount adjuster.