PROBLEM TO BE SOLVED: To achieve a focused ion beam with a small beam diameter even at a low acceleration voltage without using a complicated device configuration, thereby reducing damage on a sample.SOLUTION: The present invention relates to, for example, a focused ion beam device configured to focus ion beams from an ion source through a lens to irradiate a sample with focused ion beams. In the focused ion beam device, a four-pole element lens is arranged between an extraction electrode for extracting the ion beams from the ion source and an acceleration electrode for accelerating the ion beams.
