Provided is a method for transmitting ACK/NACK (acknowledgement/not-acknowledgement) of a terminal having a plurality of configured serving cells in a wireless communication system, which operates by means of TDD (time division duplex). The method comprises the following steps: setting the plurality of serving cells; receiving a codeword from at least one serving cell from the set plurality of service cells; and transmitting reception acknowledgement information which expresses reception confirmation of the code word, wherein when the terminal receives the code word through a first serving cell only from the set plurality of serving cells, the reception acknowledgement information is transmitted according to a first transmission method, wherein the first transmission method is a method for transmitting the ACK/NACK when the terminal is set with only one serving cell.