A Therapeutic Exploratory Clinical Study to Evaluate the Antihypertensive Efficacy of Fimasartan (BR-A-657•K) During 24 Hours in Patients With Mild to Moderate Essential Hypertension

Inclusion Criteria: * Mild to moderate essential hypertension : sitting diastolic blood pressure measured at Placebo visit and Baseline are 90\~109mmHg inclusive and the difference between sitting diastolic blood pressures measured at Placebo visit and Baseline(Day0) is under 7mmHg. * Subjects who agree to participate in this sudy and give written informed consent * Subjects considered to understand the study, be cooperative, and able to be followed-up until the end of the study Exclusion Criteria: * The sitting DBP is less than 89mmHg or more than 110mmHg or severe hypertensive patient with sitting systolic blood pressure over 200mmHg Patients with secondary hypertension * Patients with severe renal(Creatinine more 1.5mg/dl), gastrointestinal, hematological or hepatic(AST, ALT more 2 twice more than upper limit of normal)disease etc. which might affect absorption, disposition, metabolism or excretion of the drug * Patients with postural hypotension * Patients with sever insulin dependent diabetes mellitus or uncontrolled diabetes mellitus(HbA1c\>9%, regimen change of oral hypoglycemic agents within 12weeks, treated insulin before screening) * Patients with a history of myocardial infarction, severe coronary artery disease or clinically significant heart failure or valvular defect in last 6 months * Patients with consumptive disease, autoimmune disease, connective tissue disease * Patients with a history of type B or C hepatitis * Patients with HIV or hepatitis * Patients with clinically significant laboratory abnormality * Patients receiving any drugs known to affect blood pressure or medical treatments that can influence the blood pressure * Patients with allergy or contraindication to any angiotensin II receptor antagonists * Female of childbearing potential who does not undergo hysterectomy or is not post-menopausal * Patients judged to have a history of alcohol or drug abuse by the investigator * Patients participated other clinical trial 12 weeks before Screening Patients judged to be inappropriate for this study by the investigator with other reasons