The present disclosure relates to a method and an apparatus for transmitting a control channel in an intra-cell carrier aggregation system. The method includes establishing a connection with a base station through a Primary cell (Pcell) of a Time Division Duplex (TDD) scheme and a Secondary cell (Scell) of a Frequency Division Duplex (FDD) scheme. The method also includes receiving data through the Scell before a timing configured as an uplink sub-frame according to a TDD UpLink-DownLink (UL-DL) configuration of the Pcell. The method also includes transmitting a feedback of the received data through the Pcell in a feedback sub-frame. By the method, a feedback for a data can be effectively transferred.