A wireless communication apparatus that has a cross-polarized antenna structure and that is used in a wireless communication system capable of performing multiplex communication by means of MIMO (Multiple Input Multiple Output), the wireless communication apparatus comprising: a first set of antennas (210a, 210b) and a second set of antennas (210c, 210d), wherein the first set of antennas are cross-polarized with respect to the second set of antennas; a spatial multiplexing section that is configured to generate, as data to be transmitted to a communication apparatus on the other end, a plurality of streams (X 1,...X i) to be spatially multiplexed between antennas of the first and second set of antennas; and a precoding processing section that is configured, in accordance with control information fed back from the communication apparatus on the other end, to apply precoding to the plurality of streams generated by the spatial multiplexing section; characterized in that the precoding section is configured to apply a first precoding matrix to all of the spatial streams, wherein half of the precoded streams (Z 1, Z 2, S 1, S 2) are to be transmitted from the first set of antennas (210a, 210b); and to further apply a second precoding matrix only to the remaining precoded streams (Z 3, Z 4) which are to be transmitted from the second set of antennas (210c, 210d) and to which the first precoding matrix has been applied; and an antenna mapping section that is configured to transmit the precoded streams (S 1, S 2) on which only the first precoding matrix is applied from the first set of antennas, and to transmit the precoded streams (S 3, S 4) on which the first precoding matrix and the second precoding matrix are applied from the second set of antennas. a first set of antennas (210a, 210b) and a second set of antennas (210c, 210d), wherein the first set of antennas are cross-polarized with respect to the second set of antennas; a spatial multiplexing section that is configured to generate, as data to be transmitted to a communication apparatus on the other end, a plurality of streams (X 1,...X i) to be spatially multiplexed between antennas of the first and second set of antennas; and a precoding processing section that is configured, in accordance with control information fed back from the communication apparatus on the other end, to apply precoding to the plurality of streams generated by the spatial multiplexing section; characterized in that the precoding section is configured to apply a first precoding matrix to all of the spatial streams, wherein half of the precoded streams (Z 1, Z 2, S 1, S 2) are to be transmitted from the first set of antennas (210a, 210b); and to further apply a second precoding matrix only to the remaining precoded streams (Z 3, Z 4) which are to be transmitted from the second set of antennas (210c, 210d) and to which the first precoding matrix has been applied; and an antenna mapping section that is configured to transmit the precoded streams (S 1, S 2) on which only the first precoding matrix is applied from the first set of antennas, and to transmit the precoded streams (S 3, S 4) on which the first precoding matrix and the second precoding matrix are applied from the second set of antennas.