The present invention relates to a wireless communication system and, more particularly, to a method for enabling a terminal to measure the strength of an interference signal in a wireless communication system and a device therefor, wherein the method comprises the steps of: measuring a first interference strength, which is the strength of an interference signal received from a first base station group; calculating a second interference strength, which is the strength of an interference signal received from a second base station group; and correcting the first interference strength on the basis of the second interference strength.