|Ganglioneuroma of the gastrointestinal tract is a rare tumor that consists of ganglion cells, nerve fibers, and supporting cells of the enteric nervous system. Ganglioneuromas are usually associated with genetic disorders such as the multiple endocrine neoplasia syndrome or neurofibromatosis. Ganglioneuromas of the gastrointestinal tract predominantly involve the colon and rectum, and reports about duodenal ganglioneuromas are few. Herein, we report a case of duodenal ganglioneuroma treated with endoscopic resection. A 56-year-old female patient visited our hospital because of a subepithelial tumor in the second portion of the duodenum. She had no remarkable medical or family history and revealed no history of genetic disorders. Endoscopic ultrasonography and abdominal computed tomography revealed a tumor located mainly in the submucosal layer, without any regional lymph node involvement. Endoscopic resection of the lesion was performed, and the pathological examination confirmed a duodenal ganglioneuroma.