A communication relay apparatus wherein the error rate characteristic of a relay destination is improved to raise the throughput, while reducing the given interference power to prevent the reduction of the throughput of the whole communication system. In the apparatus, a signal addressed to a base station is received (ST1010), and a decoding process and other processes are performed (ST1020). A bit error determination is performed (ST1030), and if there is no bit error, a reproduction/relay process (ST1050) is performed. If there is any bit error, a threshold-based determination of reception quality is performed for each of subcarriers (ST1120-1130). If the reception quality is greater than a threshold value, the corresponding subcarrier is outputted (ST1140); otherwise, the corresponding subcarrier is not relayed (ST1150). A signal, which has been subjected to either process, is transmitted (ST1060).