A 38-year-old man was referred to our clinic with the complaint of upper abdominal discomfort. Ultrasonography and computerized tomography showed a mass occupying the left retroperitoneal space. Endoclinological results were within the normal range except for 17-OHCS and 17-KS. Preoperative diagnosis was left non-functioning adrenal tumor. Exploration was done via transperitoneal approach. The specimen weighed 100 g and was 11 x 6 x 5 cm in size. Histopathological diagnosis was ganglioneuroma of the left adrenal gland. There have been 35 reported cases with ganglioneuroma of the adrenal gland including our case in the Japanese literature and we reviewed the pathogenesis and treatment of this rare disease.