We describe an extremely rare case of an unusually presented ovarian fibroma adherent to the sigmoid colon originating from an autoamputated ovary. A 64-year-old woman was referred to our hospital with an abnormal shadow that was approximately 4 cm in diameter in the pelvic cavity detected on abdominal X-ray imaging. Computed tomography demonstrated an irregularly shaped tumor with calcification in the pelvic cavity. Laparoscopy revealed that the tumor was adherent to the surface of the sigmoid colon with a discontinuous shell and empty cavity. The left ovary was lacking, although the left salpinx and right adnexa were in their normal locations. The tumor was carefully resected with cutting of the serosa of the sigmoid colon. The serosal defect was repaired with sutures. Postoperative histopathological diagnosis was old fibroma with calcification. To the best of our knowledge, this is the first reported case of extragonadal ovarian tumor originating from an autoamputated ovarian fibroma.