A multiple-input and multiple-output, MIMO, communication method having N, where N is an integer greater than or equal to 2 transmit antennas (102a, 102b), the MIMO communication method comprising: obtaining a first digital signal sequence including I and Q digital signal sequences, the first digital signal sequence being obtained by multiplying each bit of an I-sequence and a Q-sequence in a digital signal sequence system by a first code among codes constituting n-th order, where, n is an integer, orthogonal codes, and obtaining a second digital signal sequence by multiplying I and Q digital signal sequences by a first coefficient greater than 1, the I and Q digital signal sequences being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a first code among codes constituting 2n-th order orthogonal codes; adding the first digital signal sequence and the second digital signal sequence on a bit-by-bit basis to create a first composite digital signal sequence; transmitting the first composite digital signal sequence from a first transmit antenna of a transmitting device after performing an inverse fast Fourier transform on the first composite digital signal sequence; obtaining a third digital signal sequence including I and Q digital signal sequences, the third digital signal sequence being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a second code among the codes constituting the n-th order orthogonal codes; obtaining a fourth digital signal sequence by multiplying I and Q digital signal sequences by the first coefficient greater than 1, the I and Q digital signal sequences being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a second code among the codes constituting the 2n-th order orthogonal codes; adding the third digital signal sequence and the fourth digital signal sequence on a bit-by-bit basis to create a second composite digital signal sequence; and transmitting the second composite digital signal sequence from a second transmit antenna of the transmitting device after performing an inverse fast Fourier transform on the second composite digital signal sequence. obtaining a first digital signal sequence including I and Q digital signal sequences, the first digital signal sequence being obtained by multiplying each bit of an I-sequence and a Q-sequence in a digital signal sequence system by a first code among codes constituting n-th order, where, n is an integer, orthogonal codes, and obtaining a second digital signal sequence by multiplying I and Q digital signal sequences by a first coefficient greater than 1, the I and Q digital signal sequences being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a first code among codes constituting 2n-th order orthogonal codes; adding the first digital signal sequence and the second digital signal sequence on a bit-by-bit basis to create a first composite digital signal sequence; transmitting the first composite digital signal sequence from a first transmit antenna of a transmitting device after performing an inverse fast Fourier transform on the first composite digital signal sequence; obtaining a third digital signal sequence including I and Q digital signal sequences, the third digital signal sequence being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a second code among the codes constituting the n-th order orthogonal codes; obtaining a fourth digital signal sequence by multiplying I and Q digital signal sequences by the first coefficient greater than 1, the I and Q digital signal sequences being obtained by multiplying each bit of the I-sequence and the Q-sequence in the digital signal sequence system by a second code among the codes constituting the 2n-th order orthogonal codes; adding the third digital signal sequence and the fourth digital signal sequence on a bit-by-bit basis to create a second composite digital signal sequence; and transmitting the second composite digital signal sequence from a second transmit antenna of the transmitting device after performing an inverse fast Fourier transform on the second composite digital signal sequence.