The purpose of this study is to evaluate the antihypertensive efficacy and changes of neurohormonal markers of fimasartan and atenolol with exaggerated blood pressure response during exercise in essential hypertensive patients.

After subjects have signed informed consent voluntarily, when they are taking hypertension medication, they go through screening period for 7 days including wash-out period.

After screening and wash-out period, subjects take the placebo for 14 days (Maximum 21 days), and evaluate their suitability to Inclusion and Exclusion criteria.

Patients, who evaluated the proper subject for this clinical trial, are allocated to experimental group (Fimasartan 60mg) or Control group (Atenolol 50mg) randomly at a ratio 1:1 and their investigational drugs will be administered daily for the study period (8 weeks). Subjects visit their investigators twice during treatment period, when they take their investigational drugs for 4 weeks, and 8 weeks.

The placebo period will be single-blinded and the treatment allocation in this study will be double-blinded.

Inclusion Criteria:

1. Subjects who agreed to participate in this clinical trial and submitted the written informed consent
2. Subjects aged 20 to 75 years
3. Essential hypertension patients who are measured more 140mmHg, less than 170mmHg of sitting systolic blood pressure(SiSBP) or more 90mmHg, less than 110mmHg of sitting diastolic blood pressure(SiDBP) at baseline(Day 0)
4. men who are measured more 210mmHg, women who are measured more 190mmHg or increasing more than 50mmHg after exercise at baseline(Day 0)
5. Subject who considered to understand this clinical trial, be cooperative,and able to be followed-up whole of the clinical trial period

Exclusion Criteria:

1. Patients who are measured the difference of mean blood pressure of one arm under sitting diastolic blood pressure(SiDBP) 10mmHg or SiSBP 20mmHg at screening and baseline visit
2. more 170mmHg of mean Sitting systolic blood pressure(SiSBP)or more 110mmHg of mean Sitting diastolic blood pressure(SiDBP) before exercise at baseline(Day 0)
3. Patients with secondary hypertension
4. Patients with orthostatic hypotension who has sign and symptom
5. Patients with severe insulin dependent or uncontrolled diabetes mellitus (HbA1c>9, regimen change of oral hypoglycemic agent, using insulin)
6. Patients with severe heart disease, ischemic heart disease within 6 months, peripheral vascular disease, Percutaneous transluminal coronary angiography(PTCA), Coronary artery bypass graft(CABG)
7. Patients with significant ventricular tachycardia, atrial fibrillation, atrial flutter or other significant arrhythmia
8. Patients with hypertrophic obstructive cardiomyopathy, severe obstructive coronary artery disease, aortic stenosis, hemodynamically significant aortic valve or mitral valve disease
9. Patients with severe cerebrovascular disease
10. Patients with known severe or malignancy retinopathy
11. Patients with wasting disease, autoimmune disease, connective tissue disease at present and/or previous
12. Patients with significant investigations; abnormal renal function (Creatinine more 1.5 times than upper limit of normal), abnormal liver function(AST, ALT more 2 times than upper limit of normal), severe fatty liver disease needed medication
13. Patients with surgical and medical disease that is able to be affect to absorption, distribution, metabolism and excretion
14. Patients who have a story or evidence of alcohol or drug abuse within 2 years
15. Childbearing and breast-feeding women
16. Female who plan to become pregnancy or have a possibility of pregnancy but don't prevent conception with acknowledged methods
17. Patients with Bronchial Asthma
18. Patients expected to live less than 1 year with tumor or chronic disease
19. Patients with hepatitis B or C
20. Patients with history of allergic reaction to any angiotensin II antagonist
21. Patients who took medicine within 12 weeks from screening visit or is going on the progress of other clinical trial
22. Subject who are judged unsuitable to participate in this clinical trial by investigator