A base station is provided with an assignment unit 37 for assigning an access terminal identifier to an access terminal 21 of the base station, a memory unit for storing information to permit transition into a semi connected state where the access terminal 21 saves power, while the access terminal 21 holds the access terminal identifier, and a change unit, in a case where an access terminal among the access terminals 21 having the access terminal identifiers assigned thereto is using an application for which transition into the semi connected state is effective and an access terminal identifier assigned to the access terminal 21 is not permitted to transit into the semi connected state, for changing the access terminal identifier assigned to the access terminal 21 to an access terminal identifier permitted to transit into the semi connected state based on the information stored by the memory unit 46.