Background: The purpose of this study was designed to find out the effectiveness of reposition sense, muscle fatigue response on lumbar spine after apply lumbosacral stabilization exercise program to 4 patients with chronic low back pain and for 12 weeks. Method: In this study the reposition sense was measured in 3 angle(60, 30, 12) of the lumbar spine motion with blind by MedX test machine and the difference of instability to lumbar vertebra segments in flexion, extension test of standing position and spinal load test Mattress Test by Spinal Mouse. The stabilization exercise program was applied 2 times a week for 12 weeks in hospital and 2 times a day for 20 minutes at home. Result: The results of the present study were that the repositioning sense was appeared the most error in 12 angles of lumbar flexion and Men was appeared to decrease an error more than female in average value of 4 angles after 12 weeks. And average error of male was decrease more than female. Thus the effects of lumbosacral stabilization exercise was improved repositioning sense of prorioceptor. Fatigue response test(FRT) results, in male, was raised muscle fatigue rate during increase weight, on the other hand female appeared lower than male. Conclusion: As a results, lumbosacral stabilization exercise was aided to improvement of lumbar spine repositioning sense and vertebra segments stabilization. It was showed the rate of decrease in typically 12 degree angle point of each 3 angle(60, 36, 12). Especially, that spine instability patients will have a risk when in lifting a load or working with slight flexion posture around 12 degree during the daily of living life and it is probably to increase recurrence rate. Thus, not only lumbar extension muscle strength but also stability of vertebra segments in lumbar spine may be very important.