In order to narrow down base stations within the tracking-area-based paging area to ones within a smaller area where the mobile unit may exist in a mobile communication system performing the paging on the tracking-area basis, the mobile communication system has a location registration information database memorizing tracking area information, a last location registration information and a N-th (N is an integer of one or more) location registration information from the last for each mobile unit, calculates statistical data on a movement distance for each mobile unit based on the location registration information memorized in the location registration information database, and performs the paging via base stations included both within an area whose radius is equal to the calculated statistical data on the movement distance and within the tracking area.