Purpose : The purpose of this study was to evaluate the effects of back muscle stretching on the flexibility of spinal column. Methods : The subjects were consisted of healthy adults (18 of females, 22 males ; mean aged 21.83) from 18 to 29. All subjects randomly assigned to the control group, back muscle stretching group. back muscle stretching group received back muscles stretching for 20 minutes per day and 3 times a week during 3 week period. Spine motion analyzer (Spinal Mouse) was used to measure the flexibility of spinal column. All measurement of each subjects were measured at pre-experiment, after 10 days, and after 21 days. Results : The results of this study were summarized below 1. The sacral tilt angle of the hip joint of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days(p>0.5), but differency of each group occurred at after 21 days(p<0.5). the sacral tilt angle significantly increased at the back muscle stretching group rather than the control group. 2. The thoracic vertebral tilt angle of the control group, back muscle stretching group was no significantly differences at pre-experiment, after 10 days, after 21 days(p>0.5). 3. The lumbar vertebral tilt angle of the control group, back muscle stretching group was no significantly differences at pre-experiment, after 10 days, after 21 days(p>0.5). 4. The spinal tilt angle of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days(p>0.5), but differency of each group occurred at after 21 days(p<0.5). the spinal tilt angle significantly increased at the back muscle stretching group rather than the control group(p>0.5). 5. The length of the spinal column of control group, back muscle stretching group was no significantly differences at pre-experiment and after 10 days (p>0.5), but differency of each group occurred at after 21 days(p<0.5). the length of the spinal column significantly increased at the back muscle stretching group rather than the control group(p<0.5). Conclusion : These data suggests that 3-week back muscle stretching improved the flexibility of sacrum, spinal column, and also improved spinal column lengthening. Additional randomized controlled trials to more fully investigate treatment effects and factors that may mediate these effects are needed.