The present invention relates to a wireless communication system, and to a method and apparatus for efficiently transmitting control information for supporting an uplink transmitting technique using multiple antennas. According to one embodiment of the present invention, the method for transmitting control information for an uplink transmission using multiple antennas comprises the following steps: receiving a plurality of data blocks; transmitting ACK/NACK information for the received data blocks via a PHICH; transmitting, via a PDCCH, information containing an indicator which indicates whether to retransmit each of the plurality of data blocks; and receiving an uplink transmission in accordance with the combination of the ACK/NACK information and the information indicated by the indicator.