A method for reporting a channel state for a downlink channel to be transmitted via a two-dimensional array of antenna elements consisting of one or more horizontal antenna groups and vertical antenna groups in accordance with one embodiment of the present invention, the method being performed by a terminal, comprises the steps of: receiving a channel state information-reference signal (CSI-RS) configuration for at least one vertical antenna group and a CSI-RS configuration for at least one horizontal antenna group; and calculating channel state information on the downlink channel using the received CSI-RS configurations and transmitting the channel information to a serving cell, wherein the channel state information comprises individual channel state information for a channel of the at least one vertical antenna group (hereinafter, ‘vertical channel’) and a channel of the at least one horizontal antenna group (hereinafter, ‘horizontal channel’), a combination of the individual channel state information, or joint channel state information of the vertical channel and the horizontal channel, each of which is assigned transmission priority, and the channel state information can be transmitted according to the transmission priority.