To provide a radio communication system provided with a transmitting device and a receiving device which is capable of avoiding the occurrence of a non-communicable area even when the number of frequency channels is insufficient or even when base stations cannot be placed among sufficiently short intervals and of improving an average throughput as the base station and the radio communication system.

When channel quality exceeds a predetermined value, radio signals are transmitted and received by an orthogonal frequency division multiplexing system. When the channel quality is smaller than the predetermined value, code spreading and despreading are performed by using a spreading rate which is predetermined so that a larger valued is selected as the channel quality becomes degraded, thereby transmitting and receiving the information.