The present invention relates to a pre-coding method for spatial multiplexing, comprising the steps of: performing a beam search for beam forming with a receiver device equipped with multiple antennas to perform pre-coding for spatial multiplexing in a transmitter device equipped with multiple antennas; transmitting a first packet including at least one or more training sequences to the receiver device after completion of said beam search; receiving, from the receiver device, a second packet including feedback information for pre-coding, determined in the receiver device by using the training sequences; and performing pre-coding for spatial multiplexing, onto the data stream to be transmitted to the receiver device, by using the pre-coding matrix calculated on the basis of the feedback information.