PURPOSE:To enable even a minute foreign object to be retrieved easily and in a short time by means of a scanning electron microscope by judging the level of a size of the foreign object which is provided, dividing an observation region when the level of the foreign object is equal to or less than a certain value, and retrieving each divided region successively. CONSTITUTION:A wafer 1 which was measured is carried to an optical surface foreign object inspection device 2. A foreign object information 3 is controlled by a CPU 4 within the device 2. To enlarge and observe a minute foreign object, the wafer 1 is carried to a scan-type electronic microscope 5 for observation. For example, a screen 11 of the microscope 5 is divided into 25 parts (5X5 divisions) for observing each division, thus enabling magnification for observation to be improved by five times as large as a reference magnification. Then, foreign objects 12 within 1mm on an observation CRT can be observed as those within 5 mm , thus enabling the foreign objects to be found easily. A movement for retrieval in the division region can be made speedily and accurately by using an electron beam.