Disclosed are an apparatus and a method for transmitting/receiving control information in a wireless communication system. In a repeater according to the present invention, a receiving antenna can receive control information for a hybrid automatic repeat reQuest ACKnowledgement (HARQ ACK) feedback on the data transmission of a base station from the base station through higher layer signaling. On the basis of the control information, a processor can determine a resource in an upper link control channel to be used for the transmission of the HARQ feedback. A transmitting antenna can transmit the HARQ feedback to the base station through the resource that has been determined.