Purpose : The purpose of this study was to evaluate effects of shoulder girdle stability exercise on upper extremity muscle strength. Methods : Subjects were consist of 20 people who had no disorder of upper extremity from 20 to 27 years of age during 6 weeks from April 3, 2006 to May 14. Ten of all subjects exercised muscles which stabilize to shoulder girdle for 30 minutes during 6 weeks. Biodex was used to measure upper extremity muscle strength. Results : There are increasing of shoulder flexion and extension on average torque but no statistically significant difference between pre-exercise and post-exercise. Conclusion : There are no severe difference between exercise group and non-exercise group on muscle strength.