A location registration method according to the present invention, includes: transmitting, at a mobile station (UE), a TA signal, when detecting that the mobile station (UE) has moved out of a TA list with which the mobile station (UE) is already registered by location registration processing; and transferring, from a radio base station (eNB) to an exchange (MME) identified by an exchange ID included in the TAU signal. An exchange ID assigned to a mobile station (#a) belonging to a first layer is different from an exchange ID assigned to a mobile station (#b) belonging to a second layer, even though the same exchange is identified by the exchange IDs. A TA list and a pool area set for the mobile station (#a) is different from a TA list and a pool area set for the mobile station (#b).