This clinical trial is planned to prove Entelon tab. arm is not inferior to Celebrex cap. arm in terms of the efficacy and safety through the change of K-WOMAC's total score sum in patients with osteoarthritis of knee.

Inclusion Criteria:

1. both gender,35 years ≤ age ≤ 75 years

2. patients with a diagnosis of OA(osteoarthritis) of the knee within 3 months prior to study participation, as determined by the American College of Rheumatology clinical and radiographic criteria as follows.

   1. knee arthralgia

   2. more than one case among

      • 50 years or over

        • morning stiffness less than 30 min

          • friction sound

   3. osteophyte in radiography

3. Kellgren and Lawrence Scale Grade II~III

4. total sum of K-WOMAC Scale more than 30

5. negative results in pregnancy test of urine in screening period

6. if women in childbearing age, medically reliable contraception or menopause

7. patients who give written consent of agreement to voluntarily participate in the clinical study

8. patients who can read and understand written instructions

Exclusion Criteria:

1. patients whose total sum of K-WOMAC in visit 2 is less than that in visit 1
2. fibromyalgic, anserine bursitis, infectious arthritis, rheumatoid arthritis, ankylosing spondylitis, gout or pseudogout
3. knee OA with secondary causes including major dysplastic or congenital malformation, ochronosis, acromegaly, Hemochromatosis, Wilson's disease or primary osteochondromatosis
4. anatomical malformation, disease of vertebra or other lower extremities or other disease of orthopedics which can disturb the evaluation of the target joint
5. wound, inflammation or avascular necrosis of the target joint or arthroscopy within 6 months prior to study participation
6. patients with administration of injectable hyaluronic acid to the target joint within 6 months prior to study participation
7. severe ischaemic heart diseases, peripheral artery disease and/or cerebrovascular disease, congestive heart failure, active bronchial asthma
8. medical history of malignant tumor
9. active peptic ulcer, gastrointestinal tract bleeding or inflammatory bowel disease
10. hypersensitivity with aspirin, celecoxib, corticosteroid, acetaminophen, sulfonamide derivatives or vitis vinifera or intolerance with fructose, glucose or galactose
11. continuously(1 week or more) oral or intraarticular administration of corticosteroids within 12 weeks prior to study participation
12. pregnant or lactating women
13. patients who have experience to participate in other clinical trial within 4 weeks prior to study participation
14. ALT, AST and Serum Creatinine ≥ 2×UNL
15. drug administration after diagnosing as alcoholic or psychical disease
16. patients whom the investigators judge as improper to participate in this clinical trial