Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors originating from catecholamine producing chromaffin cells in the adrenal medulla and extra-adrenal paraganglia. The overall age-standardized incidence rate is 0.18 per 100,000 person-years in Korea. The definitive treatment of PPGL is surgical excision of tumor. However, surgery is associated with a high risk of perioperative hemodynamic instability (HI). To avoid perioperative HI in patients diagnosed with PPGL, preoperative management including routine use of alpha blockade and volume expansion has been advocated by several guidelines. While unstable hypertension and tachycardia should be controlled in patients with PPGL, there is controversial that all patients diagnosed with PPGL should undergo preoperative pharmacological treatment, especially alpha blockade. The most important risk of preoperative alpha blockade use is perioperative hypotension. A recent study reported that patients diagnosed with PPGL postoperatively may have no further higher risk of intraoperative hypertension than those diagnosed preoperatively despite insufficient preoperatively management of PPGL. Therefore, it is a very important to study the relationship between HI and preoperative alpha blockade in normotensive patients diagnosed with PPGL. The aim this study is to analyze the effect and safety of omitting preoperative alpha-adrenergic blockade for normotensive pheochromocytoma through a prospective randomized controlled trial. The patients is divided into two groups. The patients in control group take a phenoxybenzamine at least 2 to 5 weeks before surgery. The patients in case group do not take a phenoxybenzamine. Primary outcome is to evaluate the percentage of time during surgery with systolic blood pressure more than 160mmHg or average blood pressure less than 60mmHg. And secondary outcomes are to evaluate hemodynamic instability in preoperative ward and postoperative ward.