A transmission station configured to transmit in an uplink communication a plurality of transmission streams from a plurality of transmission antennas (17, 18) for a multi-input multi-output communication system, the transmission station comprising: means (122, 123-1 to 123-4) for multiplying the plurality of transmission streams by a precoding matrix, the precoding matrix being an L × M matrix, L representing the number of the transmission antennas, M representing the number of the transmission streams; and means for transmitting the plurality of transmission streams that have been multiplied by the precoding matrix with the plurality of transmission antennas, the transmission station being characterized in that: when the number of the transmission antennas is 2 and the number of the transmission streams is 2, the precoding matrix is any one of a first unitary matrix obtained by the equation: U 2, 2 α θ 0, θ 1, θ 2 = exp jθ 0 1 + α 2 exp jθ 1 α exp jθ 2 − α exp − jθ 2 exp − jθ 1, wherein α represents the degree of the imbalanced amplitude and Θ0, Θ1 and Θ2 each represent a phase rotation, or a second unitary matrix obtained by rearranging the rows in the first unitary matrix, or a third unitary matrix obtained by rearranging the columns in the first unitary matrix, or a fourth unitary matrix obtained by rearranging the rows and columns in the first unitary matrix, and when the number of the transmission antennas is 2N, where N is an integer of 2 or more, the precoding matrix is formed by combining any of the first to fourth unitary matrices. means (122, 123-1 to 123-4) for multiplying the plurality of transmission streams by a precoding matrix, the precoding matrix being an L × M matrix, L representing the number of the transmission antennas, M representing the number of the transmission streams; and means for transmitting the plurality of transmission streams that have been multiplied by the precoding matrix with the plurality of transmission antennas, the transmission station being characterized in that: when the number of the transmission antennas is 2 and the number of the transmission streams is 2, the precoding matrix is any one of a first unitary matrix obtained by the equation: U 2, 2 α θ 0, θ 1, θ 2 = exp jθ 0 1 + α 2 exp jθ 1 α exp jθ 2 − α exp − jθ 2 exp − jθ 1, wherein α represents the degree of the imbalanced amplitude and Θ0, Θ1 and Θ2 each represent a phase rotation, or a second unitary matrix obtained by rearranging the rows in the first unitary matrix, or a third unitary matrix obtained by rearranging the columns in the first unitary matrix, or a fourth unitary matrix obtained by rearranging the rows and columns in the first unitary matrix, and when the number of the transmission antennas is 2N, where N is an integer of 2 or more, the precoding matrix is formed by combining any of the first to fourth unitary matrices. when the number of the transmission antennas is 2 and the number of the transmission streams is 2, the precoding matrix is any one of a first unitary matrix obtained by the equation: U 2, 2 α θ 0, θ 1, θ 2 = exp jθ 0 1 + α 2 exp jθ 1 α exp jθ 2 − α exp − jθ 2 exp − jθ 1, wherein α represents the degree of the imbalanced amplitude and Θ0, Θ1 and Θ2 each represent a phase rotation, or a second unitary matrix obtained by rearranging the rows in the first unitary matrix, or a third unitary matrix obtained by rearranging the columns in the first unitary matrix, or a fourth unitary matrix obtained by rearranging the rows and columns in the first unitary matrix, and when the number of the transmission antennas is 2N, where N is an integer of 2 or more, the precoding matrix is formed by combining any of the first to fourth unitary matrices.