Patient 1 was a 73-year-old woman with chief complaints of abdominal pain and prolapse of bowel through the anus. About 10 cm of the intestine had prolapsed through the anus, and a mass was observed at the invasive front. Computed tomography (CT) revealed the classic target sign of an intussusceptum inside an intussuscipiens, where the sigmoid colon had intussuscepted into the rectum. Patient 2 was a 92-year-old woman who presented with a chief complaint of melena. About 5 cm of the intestine had prolapsed through the anus, and a mass was observed at the invasive front. CT showed the classic target sign in the rectum. Based on physical examination and CT findings, both cases were diagnosed as intussusception caused by progression of colorectal cancer. Manipulative reduction was attempted before surgery, but neither intussusception could be reduced and thus Hartmann’s operation was performed for both patients. Patient 1 had an uneventful postoperative course and was discharged on hospital day 36. Patient 2 developed prolonged paralytic ileus due to unsuccessful mobilization and was discharged on hospital day 80. Abdominoperineal resection is required for irreducible prolapse of intussusception through the anus due to colorectal cancer, and this invasive procedure can cause complications. Many patients with this condition are elderly adults with weak pelvic supporting tissue, and thus treatment suited to each individual patient must be selected.