Abstract: There is disclosed an apparatus for locating a defect on an MR head without destroying it, if such a defect is present. The MR head has a head element, write electrode terminals, read electrode terminals, and a head electrode connected with the head element. The apparatus has a power supply and an OBIC amplifier. The power supply is connected with one of the three electrodes. The OBIC amplifier is connected with another electrode. The apparatus further includes a laser that emits a laser beam to a region containing the head element. A reflection image based on the reflected beam from the illuminated region and an internal photoelectric effect image based on a signal produced by electrical carriers induced by the internal photoelectric effect are displayed in a superimposed manner on a color CRT. This permits an operator to know where a defect is present on the MR head, if such a defect is present.