Embryonal carcinoma, a very rare ovarian germ cell tumor, involves pure and mixed phenotypes. Pure-type embryonal carcinoma has never been reported in postmenopausal women. The current case was, thus, misdiagnosed as an epithelial ovarian carcinoma based on radiologic findings. Herein, we describe the case of ovarian embryonal carcinoma in a 75-year-old woman along with a literature review. Magnetic resonance imaging findings were suggestive of epithelial ovarian malignancy associated with endometrioma, including ureteral invasion. The patient underwent complete surgical staging, and a pathologic diagnosis of pure-type embryonal carcinoma was made. The patient’s postoperative course was uneventful, and adjuvant chemotherapy was administered. Embryonal carcinoma in the postmenopausal woman is a clinical challenge owing to the possibility of its misdiagnosis as epithelial ovarian carcinoma. To the best of our knowledge, this is the first report of pure-type ovarian embryonal carcinoma in a postmenopausal woman, with a description of the clinicopathologic characteristics and review of the relevant literature.