This study examines the safety and efficacy of calcium channel blocker (CCB) in the treatment of hypertension of Autosomal Dominant Polycystic Kidney Disease (ADPKD) patients. Angiotensin receptor blocker (ARB) was shown to have kidney protecting effects in patients with renal diseases including ADPKD, glomerulonephritis and diabetic nephropathy. In case whose blood pressure is not normalized by ARB alone, CCB is selected additionally. Recent research suggests genetic calcium channel disorder is responsible for the progression of ADPKD. It is not examined clinically if CCB treatment has any harmful effect to patients with ADPKD. This study examines the safety of Cilnidipine (CCB) in the ADPKD patients whose blood pressure is not controlled under 130/85 mmHg by Candesartan (ARB) alone.