The guideline for the treatment of rectal prolapse recommends that surgeons select appropriate surgical procedures individually based on each patient's overall status. However, in cases of irreducible or incarcerated rectal prolapse, surgical options are quite limited. Here we present a case of an elderly woman with massive chronic irreducible rectal prolapse. An 87-year-old woman presented to our hospital with a complaint of massive rectal prolapse. The prolapsed rectum was over 20 cm long, and completely irreducible. She underwent perineal rectosigmoidectomy with levatorplasty known as Altemeier's procedure. More than 30 cm of rectosigmoid colon was resected. After the operation, rectal prolapse was resolved completely. Her postoperative course was uneventful, and her quality of life and bowel movements improved. She has since been healthy without recurrence for over 2 years. Altemeier's procedure is applicable even in cases of irreducible rectal prolapse and features acceptable safety and a satisfactory outcome.