It is intended to provide a rat embryonic stem cell characterized by having the following properties: (a) expressing Oct3/4 gene and Nanog gene; (b) being positive in alkali phosphatase activity; (c) being capable of forming an embryoid; (d) expressing SSEA (stage-specific embryonic antigen)-1 and SSEA-4; (e) having the same chromosomal number as normal rat cells; (f) allowing subculture while maintaining in the undifferentiated state; (g) having pluripotency in vitro; (h) being capable of differentiating into triploblastic cells; (i) being capable of forming a teratoma; and (j) being usable in the construction of a chimeric rat; a method of establishing the above-described rat embryonic stem cell, and so on.
