A radio communication system (100, 200) comprising a transmission device (1, 3) which transmits a plurality of radio signals from M, M>1, transmitting antennas, and a reception device (2, 4, 7, 7a, 8) which receives the plurality of radio signals from the transmission device using a receiving antenna and estimates, as a carrier frequency offset, a difference between a carrier frequency transmitted by the transmission device and a reference reception frequency used for reception, the transmission device comprises: a first training signal sequence generation unit (11, 31) which generates a first previously determined sequence of training signal and branches the first sequence of training signal into M; a first frequency offset assignment unit (12, 32) which assigns frequency offsets that are assigned at regular intervals and are integer times a frequency f1 to M first sequence of training signals respectively; and a transmission unit (13, 35) which transmits the radio signals including the first sequence of training signals having the frequency offsets assigned by the first frequency offset assignment unit, to the reception device via the M transmitting antennas, and in that the reception device comprises: a receiving unit (22, 42, 72, 82) which receives the radio signals from the transmission device via the receiving antenna; a first phase difference detection unit (23, 43, 73, 83) which detects first phase differences determined by the difference between a first signal which obtained by multiplying the first sequence of training signals included in the radio signals transmitted from the transmission device by a conjugate complex of a previously determined training signal and a second signal which obtained by delaying the first signal a time difference T1 that is natural number times a time represented by the reciprocal of the frequency f 1; a first averaging unit (24, 44, 74, 84) which calculates a first averaged phase difference by averaging the first phase differences of N 1 samples that are natural number times f s /f 1 samples, where f s denotes a sampling frequency, and a frequency estimation unit (25, 47, 75) which estimates the carrier frequency offset based on the first averaged phase difference. a first training signal sequence generation unit (11, 31) which generates a first previously determined sequence of training signal and branches the first sequence of training signal into M; a first frequency offset assignment unit (12, 32) which assigns frequency offsets that are assigned at regular intervals and are integer times a frequency f1 to M first sequence of training signals respectively; and a transmission unit (13, 35) which transmits the radio signals including the first sequence of training signals having the frequency offsets assigned by the first frequency offset assignment unit, to the reception device via the M transmitting antennas, and in that the reception device comprises: a receiving unit (22, 42, 72, 82) which receives the radio signals from the transmission device via the receiving antenna; a first phase difference detection unit (23, 43, 73, 83) which detects first phase differences determined by the difference between a first signal which obtained by multiplying the first sequence of training signals included in the radio signals transmitted from the transmission device by a conjugate complex of a previously determined training signal and a second signal which obtained by delaying the first signal a time difference T1 that is natural number times a time represented by the reciprocal of the frequency f 1; a first averaging unit (24, 44, 74, 84) which calculates a first averaged phase difference by averaging the first phase differences of N 1 samples that are natural number times f s /f 1 samples, where f s denotes a sampling frequency, and a frequency estimation unit (25, 47, 75) which estimates the carrier frequency offset based on the first averaged phase difference. a receiving unit (22, 42, 72, 82) which receives the radio signals from the transmission device via the receiving antenna; a first phase difference detection unit (23, 43, 73, 83) which detects first phase differences determined by the difference between a first signal which obtained by multiplying the first sequence of training signals included in the radio signals transmitted from the transmission device by a conjugate complex of a previously determined training signal and a second signal which obtained by delaying the first signal a time difference T1 that is natural number times a time represented by the reciprocal of the frequency f 1; a first averaging unit (24, 44, 74, 84) which calculates a first averaged phase difference by averaging the first phase differences of N 1 samples that are natural number times f s /f 1 samples, where f s denotes a sampling frequency, and a frequency estimation unit (25, 47, 75) which estimates the carrier frequency offset based on the first averaged phase difference.