A 57-year-old patient presented with a loss of appetite and vomiting. Gastrointestinal endoscopy revealed advanced gastric cancer with pyloric stenosis, and CT scan showed multiple liver metastases and paraaortic lymph node metastases. A gastrojejunostomy was performed because of invasion of the pancreas. After 5 courses of S-1 plus cisplatin, both the primary lesion and the paraaortic lymph nodes were reduced in size, and the liver metastases disappeared. Subsequently, a distal gastrectomy was performed. No recurrence was seen for sixteen months from treatment with the oral anticancer drug S-1. At 16 months after second surgery, progression of paraaortic lymph nodes was recognized again, and S-1 plus paclitaxel was administered. After 7 courses of S-1 plus paclitaxel, paraaortic lymph nodes became undetectable. This report describes a case of unresectable advanced gastric cancer treated by S-1 based chemotherapy and surgical method, which resulted in long survival and improvement in quality of life.