To provide a radio communication system having a system throughput improved by adjusting a traffic amount of control information, and also to provide a base station apparatus and a radio terminal.

The base station apparatus 100 for performing scheduling by allocating a band to a plurality of radio terminals in accordance with communication quality information (CQI information) to be feedbacked from the plurality of radio terminals, is provided with: a scheduling performing part 121 as a calculating means for counting the number of radio terminals being scheduling objects; a designation information generating part 123 for determining the number of bits representing communication quality information in accordance with the number of the radio terminals of the scheduling objects and generating designation information showing the number of the determined number of bits; and a transmitting part 130 for transmitting the designation information. Thus, an amount of information required for control information is reduced, and an amount of information that can be used for transmission data other than the control information is increased to provide the improved system throughput.