This invention discloses an ion beam work apparatus which comprises ion mean radiation means for focusing and radiating an ion beam extracted from an ion source to a target put on a moving mechanism, and scanning two-dimensionally the radiation position; secondary particle detection means for detecting the secondary particles generated from the target upon radiation of the ion beam; and superposition-display means for superposing the secondary particle image with a different kind of image containing such information that is not contained in the secondary particle image, and displaying the resulting image; and which can accurately position the beam radiation position to lower wiring layers of the target such as a semiconductor device that can not be observed by the secondary particle image obtained by scanning the focused ion beam.