A 69-year-old woman was admitted to a territory hospital because of severe right hypochondoralgia after 2 weeks of internal medicine for persistent epigastralgia. Gastroduodenal endoscopy revealed a large tumor with a fistula in the duodenal bulb that expanded to the stomach. Histopathologically, the biopsy specimen indicated a poorly differentiated adenocarcinoma and HER2 negative. Computed tomography revealed that the tumor invaded the left lobe of the liver. The patient was referred to our hospital for cancer treatment. After 1 course of chemotherapy with S-1 and CDDP, laparoscopic gastroenterostomy bypass was performed because of tumor hemorrhage and poor food intake. However, the tumor hemorrhage and poor food intake continued, and the tumor enlarged. Therefore, left hemihepatectomy and distal gastrectomy with resection of the duodenal bulb were performed 1 month after bypass surgery. Histological testing confirmed the diagnosis of duodenal large-cell neuroendocrine carcinoma invading the liver without lymph node metastasis. Adjuvant chemotherapy was not administered, and the patient has been alive without recurrence for 7 years and 3 months. Neuroendocrine carcinoma of the non-ampullary duodenum is very rare; however, a large cell type without lymph node metastasis may be a factor in the long-term prognosis.