Provided area a method for establishing downlink (DL) HARQ-ACK timing, and an apparatus therefor. The method establishes downlink HARQ-ACK timing when a primary cell and a secondary cell having different duplex modes are established for a user equipment. The user equipment receives a DL signal on the secondary cell. The user equipment applies HARQ-ACK timing established to be used in the duplex mode of the primary cell as HARQ-ACK timing regarding the received downlink signal.