Device and method for measurement in extension carrier

PURPOSE: A method for measuring the quality of a channel in an extension carrier and an apparatus thereof are provided to reduce inefficiency due to a reference signal by using a reference signal with diminished density. CONSTITUTION: A first message including a first indicator is received from a base station(S10). The first indicator directs control information for measuring the quality of a channel used in an extension component carrier. Control information corresponding to the first indicator is received through the extension component carrier from the base station(S30). The measurement for the quality of the channel is implemented in the extension component carrier by using the received control information(S40).