A connection request signal generation unit transmits a connection request signal to a selected neighboring base station selected from neighboring base stations existing around. A common channel reception processing unit, when receiving a response signal which corresponds to the connection request signal, from the selected neighboring base station, stores a value of transmission power with which the connection request signal is transmitted most recently, as a response time transmission power, in correspondence to the selected neighboring base station, and determines a minimum response transmission power of which value is the smallest among at least one response-time transmission power after storing the at least one response-time transmission power for the neighboring base stations; and calculate a transmission power of a common channel with which the own station should transmit, based on the minimum response transmission power. An ordinary processing unit performs a transmission through a common channel by using the common channel transmission power.