the present invention relates to a transmission - band allotting apparatus for suitably allotting a band used for transmitting a packet to each terminal in a packet radio transmission system . an object of the present invention is to provide a fair service to individual terminals , and to improve the throughput of downlink . therefore , the transmission - band allotting apparatus according to the present invention is constructed by preferentially allotting the band of the downlink to terminals in a descending order of ratios of a deviation from an average value of transmission qualities notified by the terminal and a dispersion of each of the transmission qualities .