We experienced a rare case of the rupture of the urachal diverticulum in radiation cystitis and neurogenic bladder after radical hysterectomy. A 61-year-old woman presented with severe lower abdominal pain and urinary retention. Abdominal computed tomography revealed that the urachal remnant contained a large volume of urine that leaked to subcutaneous tissue. We excised the urachal diverticulum and bladder together and created a continent urinary diversion using transverse colon. Nine months after the operation, the patient could manage clean intermittent self-catheterization 6 times a day through her umbilical stoma without any urinary complications.