PURPOSE: The purpose of this study was to investigate the effects of kinesio taping on lumbar flexibility onto erector spinae and sacroiliac joint. METHODS: Sixty healthy adults (male=36, female=24) participated in this study and were randomly assigned to the experimental group that received kinesio taping onto erector spinae and sacroiliac joint (n=30) or the control group that received X-letter placebo taping onto them (n=30). Lumbar flexibility (flexion, extension, lateral flexion, and rotation) was measured using back range-of-motion instrument (BROM) II before and after taping. RESULTS: In the change of lumbar flexibility after taping in the experimental group, there were statistically significant difference in flexion, lateral flexion, and rotation (p < 0.05), but there was no significant difference in extension. There was no significant difference in the change of lumbar flexibility after taping in the control group. CONCLUSION: In conclusion, kinesio taping onto erector spinae and sacroiliac joint improved the joint function. Kinesio taping may reduce the muscle tension and facilitate the circulation of tissue fluid. In light of these results, it is thought that the application of kinesio taping had influence on an increase in lumbar flexibility. Therefore, kinesio taping will be able to be used as the method of the prevention of pain and the treatment in the lumbar region.