An object of the invention is to stably supply an electron beam from an electron gun, that is, to prevent variation in intensity of the electron beam. The invention provides a charged particle beam device that includes an electron gun having an electron source, an extraction electrode to which a voltage used for extracting electrons from the electron source is applied, and an acceleration electrode to which a voltage used for accelerating the electrons extracted from the electron source is applied, a first heating unit that heats the extraction electrode, and a second heating unit that heats the acceleration electrode.