Abstract: According to a channel assigning method for use in a mobile communication system, a base station selects, in response to a communication connection request, a communication radio channel having an interference wave reception level which is obtained by a measuring unit and satisfies a quality conditions of a communication channel from a plurality of communication radio channels, and transmits information of the communication radio channel to a mobile station as an object of the communication connection request. The mobile station selects the communication radio channel transmitted by the base station, measures an interference wave reception level, and transmits the measurement result to the base station. The base station checks whether the measurement result satisfies the quality conditions of a communication path, and assigns the communication radio channel to the requested communication when the measurement result satisfies the quality conditions of a communication path.