A base station outputs annunciation information which corresponds to a plurality of radio cells established by a 3G public base station and an LTE public base station and which is different from annunciation information output from the 3G public base station and the LTE public base station into a target region X and forms a radio cell. A mobile station that enters the radio cell receives the annunciation information of the radio cell and executes a position registration process. An information administration device can thereby find the mobile station based on the position registration process even in the environment where a plurality of radio cells to which different frequencies are assigned are established geographically overlapping with one another.