Case images are registered so as not to cause bias (or partiality or imbalance) in amounts of feature of the case images included in a database of a similar image search system for image diagnosis. Since registration of the case images to the database is controlled according to degrees of similarity of the amounts of feature, it is possible to prevent a lot of similar case images from being included in the search result. Thus, it is possible to reduce possibility of representing a similar search result which may interfere with an accurate diagnosis by a diagnostician.
