Omental pregnancy is a very rare form of abdominal pregnancy, and can be life threatening in cases of rupture, which may lead to massive hemorrhage. A 28-year-old woman in the ninth week of amenorrhea had severe abdominal pain, and showed unstable vital signs caused by intraperitoneal hemorrhage. Emergency laparoscopy revealed large amounts of blood and blood clots in abdominal cavity, and active bleeding was observed from the right ovary. Uterus, left ovary, and bilateral fallopian tubes were grossly free. However, serum beta-human chorionic gonadotropin level increased after the operation, and histopathologic results did not show evidence of pregnancy in either right ovary or endometrium. Abdominal magnetic resonance imaging was performed and revealed a well-defined cystic mass at the lateral side of the ascending colon, suggested to be the focus of ectopic pregnancy. The patient was approached laparoscopically and consequently underwent partial omentectomy.