The present disclosure relates to a charged particle beam device intended to appropriately measure the amount of foreign substances in a vacuum chamber. As one aspect for achieving the above object, proposed is a charged particle beam device including a charged particle beam column (9) configured to irradiate a sample with a charged particle beam, vacuum chambers (1, 2) configured to create a vacuum around the sample, a plurality of electrodes (12) arranged in the vacuum chambers, and a capacitance measuring device (13) for measuring the capacitance between the plurality of electrodes.