A charged particle beam irradiation device configured to irradiate a subject to be irradiated with a charged particle beam, including: an accelerator configured to accelerate charged particles and emit the charged particle beam a gantry in which an irradiation unit for irradiating the subject with the charged particle beam is disposed an irradiation table on which the subject is positioned and a transportation line that includes an energy selection system for adjusting energy of the charged particle beam, and transport the charged particle beam to the irradiation unit from the accelerator. The transportation line is linearly formed up to the gantry from the accelerator, and at least a part of the energy selection system is disposed in the gantry, and a shield member configured to shield a radiation beam is provided between the energy selection system, which is disposed in the gantry, and the irradiation table.
