A charged particle beam device that appropriately maintains a throughput of the device for each of specimens different in a gas emission volume from each other is provided. A scanning electron microscope includes an electron source, a specimen stage, a specimen chamber, and an exchange chamber, and further includes a vacuum gauge that measures an internal pressure of the exchange chamber, a time counting unit that counts time taken when a measurement result by the vacuum gauge has reached a predetermined degree of vacuum, and an integral control unit that performs comparative calculation and determination based on a measurement result by the time counting unit and integral control based on a process flow. And, the integral control unit controls changing of a content of a subsequent process based on a shift of the degree of vacuum of the exchange chamber.