We describe a 67-year-old man with long-term CR by S-1 chemotherapy for gastric cancer with para-aortic lymph node metastases after reduction surgery. The patient presented at our hospital with epigastric pain. He was diagnosed with gastric cancer with para-aortic lymph node metastases. We performed gastrectomy and D1 lymphadenectomy without any resection of the para-aortic lymph node metastases. We treated the patient with oral S-1 chemotherapy. The initial treatment schedule was 100mg/body/day, twice daily for 4weeks with 2weeks of rest. Grade 1 neutropenia developed at the end of the second course of treatment. The regimen was changed to 2 weeks of administration, with 1 week of rest. The para-aortic lymph node metastases immediately responded to the chemotherapy. Abdominal CT showed almost complete regression of the lymph node metastases 10 months postoperatively. The patient has received S-1 chemotherapy and remained in remission for more than 5 years 6 months.