An image monitoring system may include an object area detection processing section and an object area tracking processing section. The object area detection processing section may be configured to detect object area information from an image obtained by an input image signal on a basis of the input image signal. The object area tracking processing section may be configured to perform object area tracking processing by associating a current object area with a past object area on a basis of the object area information detected by the object area detection processing section. The object area tracking processing section may associate the current object area with the past object area using unique identifying information. The object area tracking processing section may continue to retain identifying information given to a predetermined object area that has disappeared, and may give the retained identifying information to the predetermined object area when the predetermined object area reappears.