Purpose: We defined osteoarthritis of the knee as knee pain and crepitus in over 40 years old. The usual clinical manifestation include pain, stiffness, crepitus and loss of function. Methods: We studied 40 cases of the degenerative arthritis of knee clinically. The body mass index(BMI, weight(kg)/height($m^2$) was used as a measure of obesity. Pain self assessment scale by Million Index in according to age, occupation, BMI. Results: Gender by pain self assessment scale was 6.5 in male and 6.6 in female(P<0.05). The prevalence rates obese was 40%. Occupation by pain self assessment scale was 7.0 in Sitting and 5.7 in Standing(P<0.05). Prevalence was increased with age by pain self assessment scale in aged 40-69 years. Conclusion: It has been known that the obesity is one of the predispsing factors of the primary degenerative arthritis of knee. A flexion weight bearing view of the knee obtained at $30^{circ}$ to $40^{circ}$ of the joint flexion may be more sensitive in assessing damages to hyaline cartilage because the knee flexion is an important component of the stance phase.