A transceiver of a MIMO method communication system, and a transmitting-receiving method thereof are disclosed. The transceiver includes one or more antennas for receiving two or more signals transmitted using two or more transmission antennas, a channel estimating unit for estimating a channel of each of the signals, an error detecting unit for performing error detection of each signal based on reliability information added to the signal, and for determining a transmission rate of the signals based on at least one of the channel estimation result and the error detection result of each signal, and a transmission rate determining unit for adjusting the number of signals to be transmitted from the transmission antennas at a predetermined interval.