Adrenal incidentaloma refers to adrenal masses that are accidentally found on imaging performed for other reasons, without clinical symptoms of adrenal disease. Generally, adrenal masses measuring less than 1 cm are not considered adrenal incidentalomas. The purpose of radiologic examination in evaluating non-functioning adrenal incidentalomas is to distinguish between benign and malignant masses to establish the treatment plan. In this review, based on previously published research and recommendations, we describe the radiologic approach for adrenal incidentaloma and describe the imaging findings of representative diseases.