A 59-year-old man with epigastric discomfort and anorexia was referred to our hospital. Endoscopy revealed a type 3 advanced gastric cancer with pyloric stenosis diagnosed as a poorly differentiated adenocarcinoma in the biopsy specimens. A gastrojejunal bypass operation was performed because of direct invasion to the pancreas. The patient was treated by three courses of neoadjuvant chemotherapy with S-1/CDDP. Follow-up abdominal CT scan revealed that the primary tumor had become smaller, suggesting that a partial response had been achieved. Distal gastrectomy with D2 lymphadenectomy was performed. The histopathological examination showed no residual cancer cells in the primary lesion or dissected lymph nodes. Final chemotherapy efficacy was evaluated as Grade 3. The patient was treated with S-1 for one year after the gastrectomy and lymphadenectomy and has been followed up for 18 months without evidence of recurrence.