The present invention discloses a method of producing a multi-layered OFDM symbol using a plurality of small IFFT blocks. The produced OFDM symbol is able to reduce complexity in performing IFFT or FFT while maintaining orthogonality of a related art OFDM symbol. In particular, by avoiding the related art scheme using the N-sized IFFT, the layered IFFT is executed in a manner of grouping N data symbols into P groups each of which includes Q data symbols (N=P−Q). In order to produce an OFDM signal equal to that of the related art N-sized IFFT, it is preferable that phases are aligned for the data symbols on which Q-sized IFFT has been performed.