An apparatus and method for supporting both a receiver using a single antenna and a receiver using multiple antennas in a Multiple Input Multiple Output (MIMO) wireless communication system are provided. The apparatus and method in a MIMO wireless communication system include a first synthesizer for generating a first Transmit (Tx) signal by adding a first signal and a second signal, a second synthesizer for generating a second Tx signal by subtracting the second signal from the first signal and a plurality of transmitting units for transmitting the first Tx signal and the second Tx signal through corresponding antennas. Accordingly, receivers having either a single antenna or multiple antennas may be employed in the same communication system.