Purpose The purpose of this study was to determine the effect of unstable surface strength trainingon balance and lower extremity muscle activity in elderly women. Methods Our study included relatively elderly women age of 65 years or so, 14 elderly women who consented were randomized as two groups, the control group of 7 people, the experimental group of 7 people, unstable surface strength training was performed for 40 minutes a day, twice a week, for a total of 8 week. Results The experimental group had a significant difference in OLSTS and OLSTH(p<.05), the control group had a significant difference in OLSTH(p<.05). And the comparison between two groups had no significant difference (p>.05). Two groups had no significant difference in TUG (p>.05), the comparison between groups had no significant difference (p>.05). The experimental group had a significant difference in muscle activity of vastus medialis oblique and vastus lateralis oblique (p<.05), the control group had a significant difference in muscle activity of vastus lateralis oblique (p<.05), but the comparison between groups had no significant difference (p>.05). Conclusion Unstable surface strength training in elderly women were more effective than general strengthening exercises and it is an appropriate exercise to prevent from falling in the elderly.