A modulator 11 modulates an input signal in a predetermined modulation manner to generate a primary modulation signal. The serial-parallel converter 12 applies a serial-parallel conversion to a predetermined number of complex numbers and the primary modulation signal, and assigns the converted complex numbers and primary modulation signal to subcarriers to generate a subcarrier modulation signal. An IFFT calculator 13 applies an IFFT to the subcarrier modulation signal. A decomposer 14 decomposes a calculation result into real-part data and imaginary-part data. A real-part calculator 151 subtracts the average value of the maximum value and minimum value of elements of the real-part data from each element of the real-part data. An imaginary-part calculator 152 carries out a similar calculation on the imaginary-part data. A combiner 16 combines the calculated real-part data and imaginary-part data to generate a baseband signal. A transmitter 17 transmits a transmission signal generated from the baseband signal.