A communication terminal is capable of simultaneously communicating through a plurality of carriers by carrier aggregation, and the communication terminal comprises: a quality measurement unit for measuring the reception quality of a radio wave transmitted through a plurality of carriers from a base station of a connected cell to obtain a measured value; a primary carrier storage unit storing information specifying a primary carrier chosen from the plurality of carriers; a comparator for comparing a measured value of the primary carrier measured by the quality measurement unit to a threshold value; and a cell search unit for searching for another cell when the measured value of the primary carrier is less than or equal to the threshold value. Consequently, a search threshold value for carrier aggregation can be appropriately determined to perform a cell search and a quality measurement.