A reference image to serve as a reference for a non-defective determination is previously stored in association with identification information for identifying an inspection object. An image of the inspection object is displayed side by side with the reference image of corresponding identification information. A drawn position of the reference image and a drawn position of the acquired image are aligned, adjustment is made so as to make brightness of the reference image coincide with brightness of the acquired image, and adjustment is made so as to make a focus on the reference image coincide with a focus on the acquired image. Adjustment is made so as to make a focus of the reference image coincide with a focus of the acquired image.