In a mobile communication system, a mobile terminal can designate a communication quality in requesting communication. A radio base station is connected to the mobile terminal through a radio channel. A radio network controller is connected to the radio base station to control the communication quality between the mobile terminal and the radio base station. The radio network controller includes a communication request reception determination unit. Upon receiving a communication request which designates the communication quality from the mobile terminal, the communication request reception determination unit determines whether the received communication request is to be received, on the basis of a communication quality provided to communication which requests without communication quality.