We herein report the case of a 41-year-old male patient with an incidentally identified large adrenal ganglioneuroma (GN). His endocrine examinations were normal except for one episode of elevated urinary dopamine and noradrenaline levels. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) showed a large solid tumor with calcifications and a slightly lobular edge in the right adrenal gland. We performed open tumor excision and diagnosed it as adrenal ganglioneuroma. Adrenal GN is a rare benign tumor, and its hormonal activity and imaging characteristics are occasionally very similar to those of other adrenal tumors. Therefore, it needs careful evaluation by endocrine examinations and multiple imaging procedures to rule out other types of tumors.