An automatic retransmission request control system in an OFDM-MIMO communication system includes a retransmission mode selection part which selects a retransmission mode from among (a) a mode in which to transmit the data which are to be retransmitted, via the same antenna as in the previous transmission, while transmitting, at the same time, new data by use of an antenna via which no data retransmission is requested; (b) a mode in which to transmit the data, which are to be retransmitted, via an antenna via which no retransmission is requested, while transmitting new data via another antenna at the same time; (c) a mode in which to use STBC to retransmit the data via an antenna via which no retransmission is requested; and (d) a mode in which to use STBC to retransmit the data via all the available antennas.