A base station creates and transmits power control data to a mobile terminal at each prescribed time slot based on signals received from the mobile terminal, and the mobile terminal controls the transmission power of signals to the base station based on the power control data. During this transmission power control, the mobile terminal measures the reception level of common pilot signals transmitted from the base station at each time slot, calculates a moving average of the reception level for a plurality of time slots, and when transmission to the base station is interrupted, stores the transmission power and moving average for the immediately preceding time slot, and when transmission to the base station is resumed, adds the difference between the moving average at the time of transmission resumption and the stored moving average to the stored transmission power, and uses the power obtained by this addition as the signal transmission power at the time of transmission resumption.