The present invention relates to a wireless communication system. In detail, the invention relates to a method for a terminal to transmit a UCI in a carrier aggregation-based wireless communication system, and to an apparatus therefor, wherein the method involves the steps of: forming a first cell group having a PCell; forming a second cell group having one or more SCells; receiving one or more data in the second cell group; and transmitting HARQ-ACK information on the one or more data through a PUCCH, wherein, when the first and second cell groups are managed by an identical base station, the HARQ-ACK information is transmitted in the PCell, and, when the first and second cell groups are managed by different base stations, the HARQ-ACK information is transmitted in the second cell group.