A scanned image is registered in a storage unit. Attribute information for managing a registered image is set in an attribute information table. The relationship between the registered image and a related image in the storage unit is set in a related information table together with the attribute information. The storage unit is searched for an image specified by attribute information embedded in the scanned image. An image related to the image found by a search is acquired from the storage unit by looking up the related information table, and the relation view of the images is created. An operation window including the created relation view is displayed.