1. A wireless communication apparatus comprising: a processor or a circuit or a combination thereof that performs a process including: first calculating step, which calculates, from among N transformation values, wherein N is an integer equal to or greater than three, continuous in a frequency domain, only three transformation values continuous in the frequency domain from N data values, by using a discrete Fourier transform equation that is used to transform the N data values continuous in a time domain into the N transformation values continuous in the frequency domain; an obtaining step, which obtains a change in a phase difference, which is a fixed value, from the only three transformation values calculated at the first calculating step and calculating, on the basis of the obtained change in the phase difference, the phase difference between a calculated transformation value and a not-yet calculated transformation value; a second calculating, which sequentially calculates the not-yet calculated transformation value by multiplying the calculated transformation value by a twiddle factor that uses the phase difference calculated at the obtaining step as a rotation angle; and a mapping step, which maps, onto subcarriers, the only three transformation values calculated at the first calculating step and the transformation values calculated at the second calculating step, performing an inverse Fourier transformation process on the mapped transformation values, and transmitting, to a receiving device, the transformation values subjected to the inverse Fourier transformation process.