A focused ion beam apparatus having two pieces of probers brought into contact with two points of a surface of a sample, a voltage source for applying a constant voltage between the two points with which the probers are brought into contact, and an ammeter for measuring a current flowing between the two points, in which a conductive film is formed to narrow a gap thereof between the two points by operating a deflection electrode and a gas gun and the current flowing between the two points is monitored, and when the current becomes a predetermined value, a focused charged particle beam irradiated to the surface of the sample is made OFF by the blanking electrode.