A user equipment for a mobile communication system, includes: a receiver configured to receive a radio resource control (RRC) release message for transitioning the user equipment to a specific state, from a base station via a serving cell; and a controller configured to cause the user equipment to transition to the specific state in response to the reception of the RRC release message. The RRC release message includes: a radio access network (RAN) paging area identifier indicating a RAN paging area configured by the base station to the user equipment; and a public land mobile network (PLMN) identifier indicating a PLMN corresponding to the RAN paging area. The controller is configured to perform a process of transmitting a notification to a cell when the user equipment moves to the cell that does not belong to the RAN paging area after transitioning to the specific state.