A 64-year-old woman was referred to our hospital for treatment of pancreatic head cancer with acute pancreatitis due to iatrogenic injury of the pancreatic duct during endoscopic retrograde cholangiopancreatography. In addition to a 28 mm pancreatic head tumor, soft tissue shadow and fluid collection surrounding the superior mesenteric artery(SMA)due to pancreatitis were observed in the abdominal CT scan. The tumor was histologically diagnosed as adenocarcinoma by endoscopic ultrasound-guided fine needle aspiration. Neoadjuvant chemotherapy with gemcitabine and S-1 was performed to control the progression of the pancreatic cancer and improve the inflammatory changes for reduction of the operative risk. After 2 courses of neoadjuvant chemotherapy, abdominal CT scan revealed stable disease according to the Response Evaluation Criteria in Solid Tumors and attenuation of the inflammatory changes surrounding the SMA. Then, subtotal stomach- preserving pancreaticoduodenectomy was performed without the difficulty of peeling around the SMA in spite of the old inflammatory changes. Histological examination of the resected specimen showed R0 resection. The patient was discharged 18 days after surgery without any complications and is surviving 9 months postoperatively without any recurrence. Neoadjuvant chemotherapy was helpful for disease control and improvement of the inflammatory changes.