A 28-year-old woman was referred to our hospital complaining of upper abdominal discomfort. The patient had been receiving medical treatment for hypertension. Computed tomography revealed a 30 mm solid tumor with calcification in the left adrenal gland and a 8 mm nodule in the right adrenal gland. Endocrinological examinations revealed no activity of either adrenal mass. The left adrenal tumor was extirpated, because malignancy of the tumor was not ruled out. Histopathological examination proved that the tumor was ganglioneuroma arising from the extra-adrenal retroperitoneum.