The present invention provides a method for transmitting uplink control information (UCI) in a wireless access system supporting a multi-connection mode for a terminal to be connected to at least two small cells, and an apparatus therefor. In a wireless access system supporting a multi-connection mode, a method for enabling a terminal to transmit a confirmation response signal (ACK/NACK) according to an embodiment of the present invention includes the steps of: receiving an upper layer signal containing resource allotment information representing an allotted resource region in order to transmit a confirmation response signal; receiving a first physical downlink sharing channel (PDSCH) signal from a first small cell; receiving a second PDSCH signal from a second small cell; and transmitting a single confirmation response signal for the first PDSCH signal and the second PDSCH signal through the resource region represented by the resource allotment information. Here, the terminal maintains a plurality of connections with two or more small cells in the multi-connection mode, and the resource region may be allotted for the same time and frequency resource in both the first small cell and the second small cell.