Signet-ring cell carcinoma of the ampulla of Vater is so rare that only 16 cases have been reported. Here we report a case of a 47-year-old man with signet-ring cell carcinoma in the ampulla of Vater. The patient was hospitalized for right upper quadrant abdominal pain and jaundice which had developed 10 days prior. Computed tomography (CT) and ultrasonography (US) revealed dilatation of the common bile duct and the intrahepatic bile duct. On duodenoscopy, a bulging mass with an irregular margin in the major papilla was noted. Histologic findings showed a signet-ring cell carcinoma. Surgical resection was not done because lymph node metastasis was noted during the operation. Hence, conservative treatment including chemotherapy and bile drainage was done.