In a communication system in which propagation path error tolerance is improved by switching the modulation method or error correction method adaptively according to the state of the propagation path, signals MX, MY, CX, and CY indicating the modulation method and error correction method used by the transmitting side are transmitted arranged at discrete locations within the same frame. By this means, the possibility of discretely arranged signals MX and MY, or CX and CY, both degrading is made low even if the transmit signal experiences fading or propagation path fluctuations. As a result, it is possible for the modulation method information signal and/or error correction method information signal to be restored correctly on the receiving side.