To provide a composite charged particle beam device in which damage due to ion beam irradiation is reduced by aligning an electron beam and an ion beam using minimum ion beam irradiation, and further to provide a composite charged particle beam device which allows an irradiation position to be determined by electron beam irradiation even in an ion beam irradiation where it is difficult to determine the position using ion microscopic observation.

In the composite device which comprises a SEM lens-barrel 2, a FIB lens-barrel 1, and a secondary electron detector 4; the electron beam is scanned from the SEM lens-barrel on a sample plane, a negative electrical charge is electrified on the sample plane, and its microscope image (an SEM image) is observed. If a positive ion is irradiated from the FIB lens-barrel in the charged region while observing, a contrast change appears in an FIB irradiation position. The FIB irradiation position can be determined by measuring the position of the contrast change.