To improve the channel capacity of an entire communication system in accordance with transmission quality of the channels of each node. A relay node has: a receiving section that receives a received signal from a source node; a channel estimation section that measures SNR of a backward channel between the source node and the relay node, and SNR of a forward channel between the relay node and a destination node; a relay selecting section that selects, from among a QR-P-ZF method, a QR-P-QR method and a ZF-P-QR method, a relay method of the relay node in accordance with the ratio between the SNRs of the backward and forward channels; a relay signal processing section that multiplies the received signal by a transmission weight matrix corresponding to the selected relay method, and thereby converts the received signal to a relay signal; and a transmitting section that transmits the relay signal to the destination node.