The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and apparatus for transmitting uplink control information in the event that a plurality of cells is constructed, wherein the method comprises the following steps: receiving a PDCCH and/or a PDSCH; generating acknowledgement information on the PDCCH and/or PDSCH; and, if acknowledgement information transmission timing and channel state information transmission timing collide with each other, dropping the channel state information and transmitting only the acknowledgement information, or transmitting the acknowledgement information, or transmitting the acknowledgement information and the channel state information together in accordance with a predetermined condition.