Although neoadjuvant chemotherapy(NAC)is an effective treatment option for advanced adenocarcinoma at the esophagogastric junction (AEG), there is no sufficient evidence of this in Japan. We report a case of advanced AEG with pathological complete response(pCR)after NAC with S-1 and oxaliplatin(SOX). A 39-year-old man was diagnosed with advanced AEG cT3(SS)N0M0, cStage ⅡB. A total of 3 courses of SOX was administered. After the chemotherapy, the primary tumor showed a significant reduction in size. Subsequently, laparoscopic proximal gastrectomy, D1+ lymphadenectomy and double-flap technique reconstruction were performed. Histopathological examinations showed no residual cancer cells in the resected specimen. Thus, preoperative SOX therapy can be one of the useful treatment strategies for advanced AEG.