An object of this invention is to provide a method, etc., for efficiently proliferating a pluripotent epithelial somatic stem cell. A method for producing an epithelial somatic stem cell comprising Steps (A) and (B) below:(A) expressing a gene of a protein having an activity for causing a cell in G0 phase or G1 phase to enter S phase, in a cell population including an epithelial somatic stem cell； and(B) culturing the cell obtained in Step (A) in the presence of an extracellular growth factor.
