An 88-year-old woman was hospitalized with the chief complaints of lower abdominal pain, miction pain and pollakisuria. Radiographs showed a giant bladder stone shadow, 12.0 x 9.0 cm in size. Cystolithotomy was performed under the diagnosis of bladder stone. The extirpated stone weighed 510 g, and measured 10.0 x 7.5 x 6.0 cm in size. The stone had four compartments of stratified lamellae composed of calcium phosphate and magnesium ammonium phosphate. The postoperative course was uneventful and the bilateral hydronephrosis improved markedly on DIP.