A received SIR value measurement section 107 measures a received SIR (desired signal to interference ratio) value. A target SIR value setting section 108 decreases a target SIR value by a predetermined first value if the quality of received data from a demodulation section 106 is better than the desired quality, or increases the target SIR value by a second value greater than the first value if the quality of the received data is poorer than the desired quality. An SIR comparison/information generating section 109 generates transmission power control information for implementing a directive to the transmitting station to increase or decrease transmission power so that a difference between the received SIR value and the set target SIR value is eliminated. By this means, it is possible to prevent delay in updating of the target SIR value and to assure communication quality even in a case where the propagation environment deteriorates rapidly, when target SIR value updating is carried out at the time of transmission power control by means of comparison between the received SIR value and target SIR value.