The object of the present invention is to provide a radio communication system which can reduce control information transmitted from mobile stations to a base station, reduce traffic of up link radio resources, and suppress the quantity of interference to the entire radio communication system. The present invention relates to the radio communication system in which the same information is transmitted from a base station 30a to a plurality of mobile stations 40a to 40c with a predetermined down link transmission power. The base station includes transmission power controller configured to control the predetermined down link transmission power based on control information transmitted by a part of the mobile stations 40a to 40c subordinated to the base station 30a.