A base station apparatus is provided, by which a new base station (cell) can be surely added in a neighboring-cell list even when a maximum value is set for the number of base stations (cells) capable being registered in the neighboring-cell list. The base station apparatus is installed in a base station communicating with a mobile station in a mobile communication network. The base station apparatus comprises memory means of memorizing a list of peripheral base stations located at a periphery of the own base station, list-update means of adding a new peripheral base station in the list when finding the peripheral base station, and delete means of deleting at least one peripheral base station registered at an early timing in the list when the number of peripheral base stations registered in the list reaches to a predetermined maximum value that is set in advance.