Primary duodenal carcinoma excluding tumors of the ampulla of Vaterare are rare, thus, therapeutic strategy has not been established. In this study, we investigated the treatment outcome of 7 cases of duodenal carcinoma resected in our hospital between January 2010 and December 2019. The tumor locations were the duodenal bulb in 5(71%), the descending part and the transverse part in 1, respectively. Distal gastrectomy was performed in 4 out of 5 bulbous cases, and pancreatoduodenectomy was performed in the other 3 cases. The pathological stage by the 8th edition of the UICC TNM classification was Stage Ⅰ(T1a/T2, N0)in 3 cases, ⅡA(T3, N0)in 1, ⅢA(N1)in 2, and ⅢB(N2)in 1. R0 resection was achieved in all cases. Adjuvant chemotherapy with S-1 was performed in 3 of 4 patients with Stage Ⅱ or more advanced Stage. There were no tumor recurrences in 4 patients with Stage Ⅰ and Stage ⅡA, but recurrence was occurred in 2 of 3 patients with Stage ⅢA or more. The surgical outcome for duodenal carcinoma without lymph node metastasis were good. On the other hand, the prognosis for advanced cases with lymph node metastasis were poor. Thus, the development of effective adjuvant chemotherapy is strongly expected.