A 41-year-old woman was admitted to our hospital because of lower abdominal pain. She had no history of laparotomy. An abdominal CT scan at the time of admission indicated closed-loop intestinal obstruction of the small intestine within the pelvis and deviation of the uterus to the right. We diagnosed this as a strangulated internal hernia and decided to conduct an emergency operation. The ileum had herniated through a defect in the broad ligament of the uterus. The strangulated intestinal loop, which was about 25cm long, was released, and the defect of the broad ligament was closed. The postoperative course was uneventful. The differential diagnosis of intestinal obstruction should include internal hernia, especially in the absence of a previous laparotomy. An abdominal CT scan is quite useful for the preoperative and prompt diagnosis of internal hernia through a defect in the broad ligament of the uterus.