A 69-year-old man with hypertension was referred for an abnormal shadow detected on chest computed tomography(CT) at a medical checkup. Enhanced CT showed a highly enhanced posterior mediastinal tumor of 34×27 mm. Magnetic resonance imaging (MRI) revealed a low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Thus, a neurogenic tumor was suspected and the surgery was performed. The tumor was carefully dissected as it was hyper-vascular and hemorrhagic. Immediately after tumor resection, the patient's blood pressure rapidly decreased, and phenylephrine hydrochloride was needed to maintain the blood pressure. The pathological diagnosis was paraganglioma.