In the mobile terminal, the reception quality estimating unit measures a reception quality, and at least one of the data buffer monitoring unit and the transmission power monitoring unit measures a data transmission capability. Based on the measured reception quality and data transmission capability, the terminal determines a transmission mode to be used, and reports it to the base station. The base station determines the transmission mode to be practically used in accordance with the reported transmission mode, and notifies it to the mobile terminal. The base station transmits data according to the determined transmission mode, and the mobile terminal receives data according to the notified transmission mode. Thereby, the radio communication system determines the transmission mode in consideration for not only the reception quality, but also the deficiency in the data transmission capability of the terminal.