Among cellular radio communication systems, there are those in which a plurality of businesses, e.g. businesses A, B and C share a designated frequency band, and each business provides radio communication services using respectively allotted frequency bands. In this type of radio communication system, there are cases in which mobile stations belonging to different businesses use channels which have adjacent frequencies, in which case adjacent channel interference of a large interference level is produced. Therefore, in this radio communication system, of the frequency bands allotted to each business, the adjacent frequency bands which are adjacent to frequency bands allotted to other businesses are allotted to low power communications, while non-adjacent frequency bands which are not adjacent to frequency bands allotted to other businesses are allotted to high power communications.