When a sample is cut to update an observed section, an electron beam is focused on the observed section. An apparatus of the invention includes an ion gun 102 which irradiates an ion beam onto a sample 200 to form an observed section 202, an electron gun 104 which irradiates an electron beam EB onto the observed section 202 formed by the ion gun 102, a focal point adjusting unit 106 which adjusts a relationship between the observed section 202 and a focal point of the electron beam EB, and a focal point control unit 108 which controls the focal point adjusting unit 106 on the basis of an amount of cut of the sample 200 obtained by irradiation of the ion beam IB obtained by the ion gun 102.