A transmission rate control method for controlling a transmission rate of uplink user data to be transmitted by a mobile station, includes: determining, at the radio network controller, that the mobile station is shifted between a soft-handover state in which the mobile station establishes radio links with a plurality of cells and a non soft-handover state in which the mobile station establishes a radio link with only one cell; allocating, at the radio network controller, a first temporary identifier or a second temporary identifier as a common identifier for a common transmission rate control to the mobile station based on the determination of shifts; and controlling, at a cell which establishes a radio link with the mobile station, the transmission rate of the uplink user data of the mobile station using the first temporary identifier or the second temporary identifier.