The present invention relates to a wireless communication system which supports carrier aggregation. In detail, the present invention relates to a method and apparatus, wherein a mobile station changes a component carrier (CC) in a wireless communication system that supports carrier aggregation. The method comprises the steps of: receiving, from a base station, a CC reconfiguration command via one or more first preconfigured CCs; reconfiguring, in accordance with the CC reconfiguration command, CC-related information to change one or more first preconfigured CCs to a second CC; and transmitting a signal indicating the completion of CC reconfiguration to the base station after the reconfiguration of the CC-related information.