A radio communication system for transmitting a radio signal with a transmission format in which a channel response calculation preamble signal serving as a reference upon reception is inserted is disclosed. The output frequency of channel response calculation preamble signals is varied in accordance with a temporal change in radio propagation environment. A channel response variation measurement unit measures a variation of the radio propagation environment. A channel response calculation preamble signal output frequency setting unit sets the output frequency of preamble signals in accordance with the temporal change in radio propagation environment. The preamble signals are inserted in the transmission format to be transmitted at that frequency.