A method for transmitting feedback information to a base station by a user equipment, for massive antenna array based beamforming in a wireless communication system is disclosed. The method includes receiving information about a plurality of pilot patterns for a massive antenna array from the base station, estimating a plurality of channels corresponding to the plurality of pilot patterns by receiving a pilot signal based on the plurality of pilot patterns, and transmitting the feedback information for the plurality of channels to the base station, wherein the feedback information includes information about whether closed-loop beamforming or open-loop beamforming is applied to the plurality of channels and information about an effective antenna array for the plurality of channels.