The present invention relates to a method and an apparatus for transmitting a control channel in an intra-cell carrier aggregation system. A feedback method of a terminal comprises the steps establishing a connection with a base station through a primary cell (P cell) based on time division duplex (TDD) and a secondary cell (S cell) based on frequency division duplex (FDD), receiving data throughthe S cell at a subframe timing set as an uplink subframe according to TDD uplink-downlink (UL-DL) configuration of the P cell, and transmitting feedback regarding the data through the P cell in a feedback frame determined according to the subframe timing at which the data has been received. According to an embodiment of the present invention, feedback regarding data can be effectively transferred.