A UE 100 is connectable to an IP-CAN conforming to Internet protocol via any one of LTE supporting a service conforming to an IP multimedia subsystem and 3G not supporting the service conforming to the IP multimedia subsystem. In a case where the UE 100 receives a connection rejection notification from a SGSN capable of communicating with the IP multimedia subsystem after transitioning from LTE to 3G, the UE 100 suspends transmission of a request for reconnection to the IP access network only if the mobile station is camping in 3G through which the connection rejection notification has been received. Here, the connection rejection notification indicates that the UE 100 is not connectable to the IP multimedia subsystem.