We have developed a design method for artificial DNA binding protein that can bind to the promoter of specific genes on the human genome. By fusing an effector domain to this artificial DNA binding protein, we have developed an Artificial Transcription Factor (ATF) that permits the activation or suppression of target gene expression in plant and human / animal cells. We have then created an ATF that is able to bind and suppress the expression of “SOX2 gene”, an oncogene associated with both lung and esophageal cancer. We have confirmed that the introduction of ATF results in the effective suppression of SOX2 gene expression , thereby preventing lung and esophageal cancer cell proliferation.