To provide a base transceiver station and channel rate control method for enabling the base transceiver station to execute stable processing in a radio communication system compliant with an HSDPA communication scheme, a base transceiver station 5 compliant with high speed downlink packet access is comprised of a Uu rate calculating section 16 that obtains radio quality between a radio access network 2 and a mobile terminal 6, a Ui rate calculating section 15 that obtains channel quality between the station 5 and a radio network controller 4, a CPU utilization measurement function section 17 that measures the CPU utilization of the station 5, and a CA calculating section 14 that calculates a permissible data amount using the radio quality, channel quality and CPU utilization.