A transmission method of multiple antennas with two antennas, said two antennas being antenna 1 and antenna 2, said transmission method comprising steps of: generating information bits to be transmitted by the respective two antennas; mapping the information bits to be transmitted by the respective antennas into symbols; multiplying, by a constant, a vector constituted by the symbols to generate a resulting vector; and transmitting symbols of the resulting vector by the multiple antennas, wherein the symbols transmitted by the respective antennas and symbols previously transmitted by the respective antennas constitute a matrix having an orthogonal property, wherein for retransmission according to hybrid automatic repeat request, HARQ, with the two antennas: in a first transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to quadrature phase shift keying, QPSK constellation points in an order of b 0 b 1 and in an order of b 2 b 3, respectively; in a second transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to the QPSK constellation points in an order of b 3 b 2 and in an order of b 0 b 1, respectively; in the first transmission, mapping is performed in accordance with a first remapping version; and in the second transmission, mapping is performed in accordance with a second remapping version, wherein modulation mapping rules of the first and second transmissions are defined in accordance with the following table: Remapping Version Modulation Mapping Rules Symbol 1 Symbol 2 0 b 0 b 1 b 2 b 3 1 b 3 b 2 b 0 b 1 generating information bits to be transmitted by the respective two antennas; mapping the information bits to be transmitted by the respective antennas into symbols; multiplying, by a constant, a vector constituted by the symbols to generate a resulting vector; and transmitting symbols of the resulting vector by the multiple antennas, wherein the symbols transmitted by the respective antennas and symbols previously transmitted by the respective antennas constitute a matrix having an orthogonal property, wherein for retransmission according to hybrid automatic repeat request, HARQ, with the two antennas: in a first transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to quadrature phase shift keying, QPSK constellation points in an order of b 0 b 1 and in an order of b 2 b 3, respectively; in a second transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to the QPSK constellation points in an order of b 3 b 2 and in an order of b 0 b 1, respectively; in the first transmission, mapping is performed in accordance with a first remapping version; and in the second transmission, mapping is performed in accordance with a second remapping version, wherein modulation mapping rules of the first and second transmissions are defined in accordance with the following table: Remapping Version Modulation Mapping Rules Symbol 1 Symbol 2 0 b 0 b 1 b 2 b 3 1 b 3 b 2 b 0 b 1 in a first transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to quadrature phase shift keying, QPSK constellation points in an order of b 0 b 1 and in an order of b 2 b 3, respectively; in a second transmission of the information bits according to the HARQ, the antenna 1 and the antenna 2 transmit bits that are mapped to the QPSK constellation points in an order of b 3 b 2 and in an order of b 0 b 1, respectively; in the first transmission, mapping is performed in accordance with a first remapping version; and in the second transmission, mapping is performed in accordance with a second remapping version, wherein modulation mapping rules of the first and second transmissions are defined in accordance with the following table: Remapping Version Modulation Mapping Rules Symbol 1 Symbol 2 0 b 0 b 1 b 2 b 3 1 b 3 b 2 b 0 b 1