On the transmitting side a spread modulated signal that has undergone spread spectrum processing and an information modulated signal that has not undergone spread spectrum processing are multiplexed in a same frequency band. On the receiving side the specific modulated signal is first demodulated by a spread spectrum demodulation section 1803, then a replica signal of the specific modulated signal is generated by a spread spectrum modulated signal regeneration section 1805, and the information signal that has not undergone spread spectrum processing is extracted by eliminating the replica signal from the multiplex signal. By this means, even when a large number of information signals are transmitted in a same frequency band, these signals can be separated and demodulated satisfactorily on the receiving side.