Change detecting method and apparatus and monitoring system using the method or apparatus

A change detecting apparatus and monitoring system using the apparatus as a notification apparatus. The change detecting apparatus has an input unit receiving a monitor image captured by a pickup unit, a region specification unit specifying N regions (N>=2) in the monitor image, a notification destination specification unit specifying notification destinations of image changes in the monitor image in advance according to the image change characteristics, a change detection unit detecting an image change in the N regions, a characteristics extraction unit extracting a feature of the image change, a monitor information generation unit generating monitor information related to the detected image change and a transmission unit transmitting the monitor information. Based on the detected image change characteristics, the monitor information is transmitted to a notification destination set in the notification destination specification unit.