For radio communications between a base station and a mobile station, resource allocation within a resource block including control resources used for control signals (CQI, ACK/NACK) and reference resources used for a reference signal is performed. The base station measures the quality of a channel between the mobile station and the base station itself. Based on the measured channel quality, the base station sets a ratio between resources for the control signals CQI and ACK/NACK in the control resources, and notifies the mobile station of the set resource ratio.