PROBLEM TO BE SOLVED: To provide: an anticancer agent for a head and neck cancer and an esophageal cancer having excellent effect on the head and neck cancer and the esophageal cancer； and a potentiator enhancing the effect of the anticancer agent on the head and neck cancer and the esophageal cancer.SOLUTION: The anticancer agent for a head and neck cancer or an esophageal cancer includes (a) and (b) as active principles: (a) a double stranded RNA having the RNAi effect on the RECQL1 gene or the WRN gene； and (b) a DNA capable of expressing a double stranded RNA having the RNAi effect on the RECQL1 gene or the WRN gene. The potentiator enhancing the effect of the anticancer agent on a head and neck cancer or an esophageal cancer includes (a) and (b) as active principles: (a) a double stranded RNA having the RNAi effect on the RECQL1 gene or the WRN gene； and (b) a DNA capable of expressing a double stranded RNA having the RNAi effect on the RECQL1 gene or the WRN gene.
