Objectives: The purpose of this study was to develop a non-suicidal self-injury (NSSI) prevention program for adolescents and confirm its effectiveness in primary prevention by applying dialectical behavior therapy skills training (DBT-ST). Methods: From September to December 2021, 217 first-year students in three middle schools in the Chungcheong Province were tested for changes from before and after the program using the Responses to Depressed Mood Questionnaire and Difficulties in Emotion Regulation Scale-16 using paired t-tests. McNemar’s test was conducted to confirm the changes in the perception and attitude scale of NSSI for each question. Results: A comparison of the changes from before and after the program revealed that the response to depressed mood (t=7.93, p<0.001), ruminant response (t=5.18, p<0.001), and distractive response (t=6.07, p<0.001) which are subfactors of the response to depressive moods, were significantly affected. There was a significant decrease in the difficulty in performing goaloriented behavior (t=3.34, p=0.01) and lack of emotional clarity (t=2.52, p=0.012), which are subfactors of emotional regulation difficulties. Also, in the comparison of the perception and attitude towards NSSI, statistically significant changes were confirmed in 7 out of a total of 9 questions (p<0.001). Conclusion It was confirmed that this program developed by applying DBT-ST was effective in the primary prevention of NSSI for adolescents.