A radio base system (1000) is multi-path-connected to a plurality of mobile terminal devices to transmit/receive signals. When a communication channel establishment request is sent from one of the plurality of mobile terminal devices, a control unit (80) detects the presence or absence of a mobile terminal device to which a communication channel is already connected for each of a plurality of slots. When channel allocation has to be performed by path multiplexing on the mobile terminal device which has sent the channel establishment request, control unit (80) permits channel establishment in accordance with a result of detection of an error detecting unit (56).