[Problem] To provide a novel and effective method for treating cancer, method for preventing cancer, and method for suppressing metastasis by targeting cancer stem cells, the methods being capable of labeling and damaging cancer stem cells and to provide a method for damaging and a method for identifying cancer stem cells. [Solution] The present invention provides a viral vector having a promoter that is specifically expressed in cancer stem cells and that can be used for treatment and diagnosis.Furthermore, the present invention provides a method for treating cancer, a method for preventing cancer, and a method for suppressing metastasis using this viral vector, and further provides a method for damaging and a method for identifying cancer stem cells. Furthermore, the present invention provides a labeling agent and a toxic agent for cancer stem cells containing the vector as the active ingredient, and further provides a diagnostic drug, a therapeutic drug, and a metastasis suppressant for cancer.
