Endometriosis is common in women of reproductive age, which can involve the intestinal tract. However, large bowel obstruction is an extremely rare complication of colonic endometriosis. In this article, we present a case of intestinal endometriosis with the symptom of rectal bleeding in the menstrual period for 1 year. Colonoscopy showed a semicircular tumor with luminal narrowing at rectosigmoid junction. The pathology of biopsy specimen revealed endometrial glands by repeated check after reviewing the patient's history. Surgical resection was performed because of luminal stricture. Intestinal endometriosis should always be kept in mind as a differential diagnosis in reproductive‐aged female patients who have symptoms of gastrointestinal bleeding and abdominal pain in the menstrual period.