The present invention relates to a method for feeding back channel state information with respect to downlink transmission of a terminal in a wireless communication system supporting multiple antennas. Particularly, the method comprises the steps of measuring a channel with respect to downlink transmission; and transmitting a precoding matrix indicator (PMI) to which a precoding matrix for multiple antennas is applied, on the basis of the channel measuring result, wherein the multiple antennas are defined as a group of N antenna (N>0, N is an integer), and the precoding matrix for multiple antennas is determined by a precoding matrix for the group of N antennas and a phase coefficient matrix with respect to the precoding matrix for the group of N antennas.