qRT-PCR primers capable of detecting EML4-ALK gene variant based on circulating tumor cells at a more sensitive detection limit than a conventional method. Also disclosed is a lung cancer patient screening method which is capable of detecting EML4-ALK gene variant using circulating tumor cells even in a lung cancer patient on whom ALK-FISH testing has been difficult to perform, due to difficulty in collecting a solid lung cancer tissue sample, and is able to determine whether an anticancer drug targeting the EML4-ALK gene variant may be applied to the lung cancer patient.