In a communication system and a communication method using a TDD-OFDMA communication method, inter-carrier interference due to delay dispersion is prevented by suppressing the delay time within a guard interval.In a base station device 10, based on a pilot symbol included in uplink information transmitted from a terminal device 20 through an assigned channel assigned by a channel assignment response, it is estimated whether a received timing of receiving the uplink information is early or late, the received timing estimation result is recorded in a timing recording unit, and when transmitting downlink information from the base station device 10, a transmission timing request is added to the downlink information based on content recorded in the timing recording unit and the downlink information is transmitted to the terminal device 20 (Step S15), and in the terminal device 20, the received transmission timing request is recorded in a transmission timing recording unit, and uplink information is transmitted from the terminal device 20 to the base station device 10 at a timing instructed by a transmission timing request (Step S16).