To attain multiplex transmission of information efficiently with small effect of disturbance by configuring a transmission with plural secondary modulation sections and spread signal synthesis sections and configuring a receiver with a spread signal distribution section and a spread code demodulation section.

A video signal and a voice signal are digitized by input sections 1, 2 respectively and primary modulation sections 3, 4 multiply a sine carrier with the result to generate a narrow band signal. Modulation sections 5, 6 multiply respectively spread codes a, b of the video and voice signals with the generated signal to generate spread signals a7, b8. An adder 9 adds the signals a7, b8 to generate a code multiplex signal and it is sent via a transmission section 10 and a transmission antenna 11. On the other hand, a reception section 22 receives a radio wave via an antenna 21 and a distributer 23 is used to distribute the multiplex signal 24 into two, they are multiplied with the spread codes a, b respectively at 1st and 2nd demodulation sections 25, 26, 2nd demodulation sections 27, 28 demodulate the video signal and the voice signal respectively and they are respectively outputted from output sections 29, 30.