The focused ion beam apparatus includes: a vacuum container; an emitter tip disposed in the vacuum container and having a pointed front end; a gas field ion source; a focusing lens; a first deflector; a first aperture; an objective lens focusing the ion beam passing through the first deflector; and a sample stage. A signal generator responding to the ion beam in a point-shaped area is formed between the sample stage and an optical system including at least the focusing lens, the first aperture, the first deflector, and the objective lens, and a scanning field ion microscope image of the emitter tip is produced by matching a signal output from the signal generator and scanning of the ion beam by the first deflector with each other.