Purpose : The aim of this study is to compare the trunk muscle activities in trunk stabilization on the stable and unstable supporting surfaces using by sEMG. Methods : The subjects of this study include seventeen male. We measured sEMG activities of rectus abdominis and erector spine in subjects during trunk stabilization such as plank exercise, quadruped position, quadruped position with rising hand and foot on the stable and unstable surface. Results : sEMG activities in plank exercise was significantly higher in left rectus abdominis and left erector spine on unstable surface then stable surface (p<.05). sEMG activities of left rectus abdominis and left erector spine in quadruped position was significantly higher in unstable surface than stable surface (p<.05). In comparison with posture, Plank exercise showed a significant difference increase other postures (p<.05). Conclusion : sEMG activities of muscle in trunk stabilization was significantly higher in unstable surface than stable surface and plank exercise. So, we suggest that trunk stabilization on the unstable supporting surface and plank exercise were more effective method than stable surface to improve trunk muscles activities.