The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for reporting channel state information, wherein the method comprises the steps of: receiving configuration information for a period report of CSI from a first transmission point; and transmitting, to said first transmission point, a CSI report for the downlink of a transmission point corresponding to a corresponding subframe among a plurality of transmission points through each subframe that is periodically set according to said configuration information, wherein: one or more subframes corresponding to a second transmission point are used to transmit a CSI report for multi-transmission point cooperative transmission, if rank information reported to said first transmission point prior to said CSI report is a critical value or less; and one or more subframes corresponding to said second transmission point are used to transmit a CSI report for single-transmission point transmission, if the rank information reported to said first transmission point prior to said CSI report is said critical value or more.