A 81-year-old woman was referred to our department for further examination and treatment after upper gastrointestinal endoscopy revealed a type 3 tumor in the antrum. CT scan revealed a primary tumor with extramural invasion in the antrum and large lymph nodes bordering the pancreas, as well as in the right side of cardia. A diagnosis of advanced gastric cancer cT4aN2M0, cStage Ⅲ was made. She was administered chemotherapy with nivolumab and SOX. After 2 courses of treatment, CT scan showed marked reduction of the primary tumor and lymph nodes. Therefore, laparoscopic gastrectomy(D2 dissection+Roux-en-Y reconstruction)was performed. Histopathological findings showed that the primary tumor was confined to the sub serosal tissue and no lymph node metastases were observed. The patient is currently alive without recurrence and treated with S-1 monotherapy. Chemotherapy with nivolumab and SOX is considered to be an effective treatment strategy for advanced gastric cancer with advanced lymph node metastases.