The peak-index calculator calculates a peak index as an indication of PAR in accordance with gain factors β of channels. The coefficient selector includes a lookup table storing therein fitting coefficients X and Y each categorized in accordance with a combination of β, and selects coefficients X and Y each having a value determined in accordance with a combination of the gain factors β. The power-reduction calculator calculates a reduction in maximum signal-transmission power in accordance with both the peak index and the selected coefficients X and Y. The TXAGC calculator controls maximum signal-transmission power in accordance with the calculated reduction.