The present invention is to provide a mobile radio communications method, a mobile radio communications system, base station controlling equipment and a mobile radio terminal device, all of which make it possible to realize reduction of power consumption of the mobile radio terminal device even in the case where the remaining battery capacity of the mobile radio terminal device has become short while the mobile radio terminal device is performing high-speed and large-amount data transmission. In the present invention, the mobile radio terminal device detects the remaining battery capacity, and this information is transmitted to the base station controlling equipment. Then, the base station controlling equipment recognizes the remaining battery capacity of the mobile radio terminal device, and in the case where it is recognized that the remaining battery capacity of the mobile radio terminal device has become insufficient to continue the data transmission with a high rate, the base station controlling equipment changes the data transmission rate to a low speed rate for performing a reducing power consumption mode in the mobile radio terminal device.