A 49-year-old female presented complaining of gross hematuria. Cystoscopy and magnetic resonance imaging revealed a papillary tumor on the bladder dome. At biopsy pathology the tumor was diagnosed as adenocarcinoma. We diagnosed the tumor as urachal adenocarcinoma and performed partial cystectomy of bladder dome with en-bloc resection of the urachal ligament up to the umbilicus. In surgical pathology, the tumor had invaded to the fat tissue around the urachal ligament with metastasis to the lymph node. Therefore the tumor was diagnosed as a stage IVA (Sheldon's category) urachal adenocarcinoma. After surgery, 6 cycles of chemotherapy with TS-1 and cisplatin (CDDP) were performed. There has been no relapse 5 years after surgery. This is the first report of successful adjuvant chemotherapy with TS-1/CDDP for advanced urachal adenocarcinoma.