A modulator generates modulation signals from input signals. A combiner arranges subcarrier modulation signals based on the modulation signals in order thereby to generate a compound matrix. The shifter shifts elements of each row of the compound matrix to generate shift matrix. An IFFT calculator subjects the shift matrix to inverse fast Fourier transformation to generate inverse transformation matrix. A maximum detector detects a column with a highest peak-to-average power ratio among columns of the inverse transformation matrix. A minimum detector detects an inverse transformation matrix including a column with a lowest peak-to-average power ratio among columns of inverse transformation matrices detected by the maximum detector. A transmitter generates a transmission signal based on baseband signals generated from each column of the inverse transformation matrix detected by the minimum detector, and transmits the transmission signal.