A mobile communication system includes a first and second systems. Each of the first and second systems has a land station and at least one mobile terminal capable of communicating with the land station. The land station of the first system has a broadcasting channel transmission unit for transmitting status information via a broadcasting channel, and the mobile terminal of the second system has a broadcasting channel receiving unit for receiving information in the broadcasting channel to obtain a broadcasting channel receiving condition and the status information, a giving interference estimation unit for estimating giving interference level onto communication of the first system by the second system based upon the obtained broadcasting channel receiving condition and the obtained status information, and an output signal level control unit for controlling output signal level of the mobile terminal of the second system based upon the estimated giving interference level.