A charged particle beam device includes a lens barrel having a charged particle source, a sample chamber in which a sample to be irradiated with a charged particle beam is provided, and a heat emission type electron source disposed in the sample chamber and maintained at a lower potential than that of an inner wall of the sample chamber, in which the inside of the sample chamber is cleaned by electrons (e−) emitted from the heat emission type electron source after a heating current is generated by applying a voltage from an electron source power supply. The heat emission type electron source is maintained at a lower potential than that of the inner wall of the sample chamber by applying a negative voltage to the heat emission type electron source using a bias power supply. A magnitude of the negative voltage applied to the heat emission type electron source is preferably about 30 to 1000 V, particularly preferably about 60 to 120 V.