PURPOSE: To attain sure connection without movement of a mobile station even when a communication traffic is concentrated locally or a fault takes place in a radio base station with respect to the communication control circuit system of mobile communication.

CONSTITUTION: A channel management means 12 manages a communication channel used by a communication controller 11 for the communication with a host station such as a radio line control station and a mobile station 100 at present and outputs number of communication channels in use. A transmission power command means, 13 receiving number of channels from the channel management means 12 outputs a decrease command when the channel number is increased and outputs an increase command when the channel number is conversely decreased. An amplifier 5 decreases the amplification factor of the transmission power for a control channel when the decrease command comes from the transmission power command means 13 and increases the amplification factor of the transmission power for the control channel when the increase command comes from the transmission power command means 13.