In a radio communication system, when switching of a multicast communication and a unicast communication is performed, a radio communication base station determines whether to switch a communication mode based on reception information received from a mobile terminal, newly establishes a logical channel between the mobile terminal and the radio communication base station by the same logical channel as before switching based on the determination result, converts to a transport channel of a communication mode different from before switching in the newly established logical channel, and switches communication with each mobile terminal to a communication mode represented by the converted transport channel. Thus, switching of the communication mode is performed limitedly only in between the radio communication base station and each mobile terminal.