A radio device in a first base transceiver station for communicating with a mobile station located in a radio propagation area of the first base transceiver station, the radio device includes a test target selection processing unit for identifying a mobile station located in an area covered with both the radio propagation area of the first base transceiver station and a radio propagation area of a second base transceiver station established adjacent to the first base transceiver station, and a test request processing unit for transmitting a test request signal having information concerned with the second base transceiver station to the mobile station identified by the test target selection processing unit so that the mobile station executes a connection test on the second base transceiver station, and for processing a test result signal responded by the mobile station.