In a panoramic image construction technology of dividing a wide-range imaging area (EP) of semiconductor patterns into a plurality of imaging areas (SEP), and joining a group of images, which are obtained by imaging the SEPs using an SEM, through image processing, a fact that although a pattern serving as a key to joining is not contained in an overlap area between some of the SEPs, all the images can be joined in some cases is noted so that: although the number of patterns serving as keys to joining is small, SEPs whose images are all joined can be determined; or even if such SEPs cannot be determined, SEPs satisfying user's request items as many as possible can be determined. The cases are extracted by optimizing an SEP arrangement, whereby the number of cases in which SEPs whose images are all joined can be determined is increased.