Provided are a method for transmitting an ACK/NACK by a terminal configured with a plurality of serving cells, and a terminal using such a method. The method comprises: receiving data from a downlink subframe of a first serving cell; and transmitting the data for the ACK/NACK signal from an uplink subframe of a second serving cell; wherein the uplink subframe is determined in accordance with the ACK/NACK timing of the first serving cell, or the ACK/NACK timing of the second serving cell if the data is received from a downlink subframe of the second serving cell, which is identical to the downlink subframe of the first serving cell.