A 65-year-old woman was admitted with upper abdominal pain and pyrexia. She was given a diagnosis of acute pancreatitis and treated with intravenous infusion. After recovering, abdominal enhanced-CT showed a low density area in the head of the pancreas, measuring 2 cm in maximum dimension. Endoscopic ultrasound guided fine-needle aspiration (EUS-FNA) revealed acinar cell carcinoma (ACC). She underwent curative subtotal stomach-preserving pancreaticoduodenectomy. The definitive diagnosis, based on the histopathological examinations including immunohistochemical staining, was ACC. ACC of the pancreas is extremely rare, occurring in approximately 1% of all cases of pancreatic neoplasm. We report a rare case diagnosed as ACC by EUS-FNA prior to surgical treatment.