The present invention discloses a method and an apparatus for reporting channel state information. According to one embodiment of the present invention, receiving a channel state information-reference signal (CSI-RS) based on CSI-RS setting information that is provided by a base station; and reporting to the base station the CSI generated by using the CSI-RS, wherein the CSI includes precoding information selected from a specific codebook, wherein elements of the specific codebook are configured based on a precoding vector W, wherein the precoding vector W is W = [ W ⁢ ⁢ 1 aW ⁢ ⁢ 2 ] , W1 is a precoding vector applied to a first domain antenna group having a 2D antenna structure, W2 is a precoding vector applied to a second domain antenna group having the 2D antenna structure, and wherein “a” can be a value representing phase difference between the first domain antenna group and the second domain antenna group.