A wireless communication system is disclosed. A method for transmitting uplink control information in a wireless communication system supporting carrier aggregation and operating in TDD includes: generating a first HARQ-ACK (hybrid automatic repeat request—acknowledgement) set for a first cell using a value M; generating a second HARQ-ACK set for a second cell using the value M; and transmitting a bit value corresponding to a third HARQ-ACK set including the first HARQ-ACK set and the second HARQ-ACK set in an uplink subframe n, wherein M=max(M1, M2), max(M1, M2) representing a value being equal to or larger than not smaller between M1 and M2, wherein M1 corresponds to the number of downlink subframes corresponding to the uplink subframe n in the first cell, and M2 corresponds to the number of downlink subframes corresponding to the uplink subframe n in the second cell, wherein the first cell and the second cell have different UL-DL configurations.