In a MIMO system using a cross-polarized antenna structure, even if no ideal XPD can be obtained, the interference between different polarized waves can be reduced to allow an effective precoding to be executed. When a MIMO communication is performed between a transmitter and a receiver each using a cross-polarized antenna structure, a channel estimating and precoding selection section of the receiver performs a channel estimation of MIMO channels from the transmitter to the receiver, decides a precoding matrix of a projection matrix for mutually orthogonalizing or substantially orthogonalizing the channel response matrixes for respective different polarized waves, and feeds the determined precoding matrix back to the transmitter. In the transmitter, a precoding processing section applies the precoding matrix to the spatial stream corresponding to one of the polarized waves to perform a precoding, thereby allowing the transmitter to transmit the polarized waves with the orthogonality therebetween maintained.