The purpose of this study to identified the effect of muscle strengthening of ankle joints on postural sway. The subjects of this study were 29 healthy adults aged between 20 and 30 years(male 18, female 11). All subjects received ankle muscle strengthening exercise for 3 times, 3 sessions, 30 minutes per week over 4weeks period. The measured item of muscle strength, postural sway. Data collected from all subjects the result were as follows. The ankle strength showed significant increase(p<.05). One leg stand test with eye close increase in static balance(p<.05), left-right sway distance and anterior-posterior sway distance with eye open and close in static balance(p<.05). The result findings show that strength of the ankle joint muscles is a factor which affects postural sway and the ankle joints are important in static balance.