The present invention relates to a method and apparatus for transmitting uplink control information (UCI) in a carrier aggregation system wherein a plurality of serving cells is aggregated. The method comprises the steps of: receiving a downlink signal through at least one of the serving cells; generating first UCI and second UCI responding to the downlink signal; transmitting the first UCI through a first serving cell; and transmitting the second UCI through a second serving cell. The first serving cell and the second serving cell are different from each other, and the first UCI and the second UCI are different kinds of uplink control information than each other.