In a search mode of an electronic endoscope system, ordinary light images and special light images are captured from a body cavity respectively under white light and special light. Simultaneously, biological information on the body cavity is acquired from image signals obtained under the special light. The ordinary and special light images are associated with the acquired biological information and stored in an image accumulator. By pressing a lock-on switch while confining a target in an area designating frame on an ordinary image on a monitor, the target is designated and biological information on the target is determined. Thereafter, biological information associated with the latest image in the image accumulator is compared with the biological information on the search target. If the latest image contains an area having the same biological information as the search target, the area designating frame is displayed on that area on the monitor.
