By using a discrete Fourier transform equation that is used to transform N data values (N is an integer equal to or greater than one) to N transformation values, a wireless communication apparatus calculates three continuous transformation values from the N data values. Then, the wireless communication apparatus obtains a fixed change in the phase difference from the three calculated transformation values; multiplies the calculated transformation value by a twiddle factor that is obtained from the change in the phase difference; and calculates not-yet calculated transformation values.