A transmission rate control method including: notifying, from the mobile station UE to the radio base station NodeB, a data amount in a transmission buffer of the mobile station UE; determining, at the radio base station NodeB, a maximum allowable value that can be notified to the mobile station UE, in accordance with the data amount in the transmission buffer; calculating, at the radio base station NodeB, as a granted value to be notified to the mobile station UE, a value that does not exceed the maximum allowable value, notifying, from the radio base station Node B to the mobile station UE, the granted value calculated at the radio base station UE, by using a transmission rate control channel; and transmitting, at the mobile station UE, the uplink user data, at a transmission rate corresponding to the granted value notified from the radio base station NodeB.