A base station apparatus is provided, by which a downlink transmission power (transmission output) can be properly set and frequent handovers of a mobile station (user equipment) can be prevented to occur. The base station apparatus is installed in a small-cell base station communicating with a mobile station in a mobile communication network, and provided with measurement means of measuring a time interval between a timing of receiving a handover request from a macro-cell base station when a mobile station performs a hand-in from a macro cell to a small cell and a timing of receiving information showing a failure of handover from the macro cell to the small cell, from the macro-cell base station, in sate that the small-cell base station is located in the macro cell or neighboring the macro cell and control means of controlling so as to decrease a setting of downlink transmission power based on the time interval measured by the measurement means.