To improve the frequency utilization rate of a radio communication channel and to attain the reduction of loss probability by allocating radio communication channels less than the number of radio communication channels to mobile stations corresponding to plural communication classes requested from the mobile stations.

The mobile station transmits a request signal requesting the allocation of radio communication channel designating any communication class to be used out of plural communication classes. Then, a base band signal processing part 22 at a radio base station decodes the requested communication class from this request signal, and a storage part 25 stores the maximum number of allocation channels and required communication quality corresponding to the plural communication classes previously requested by the mobile station. Further, based on these decoded result and stored information, a processing part 24 allocates the radio communication channels, which are less than the maximum number of allocation channels and less than the number of radio communication channels among idle radio communication channels satisfying the required communication quality corresponding to the requested communication class, to that mobile station.