A transmission rate control method according to the present invention includes: determining, at the radio base station NodeB, a maximum granted value that can be notified to the mobile station UE, in accordance with the happy bit notified from the mobile station UE; calculating, at the radio base station NodeB, as an allowable value to be notified to the mobile station UE, a granted value not more than the maximum granted value; notifying, from the radio base station NodeB to the mobile station UE, the granted value calculated at the radio base station NodeB, by using a transmission rate control channel; and transmitting, from the mobile station UE, the uplink user data, at a transmission rate corresponding to the granted value notified from the radio base station NodeB.