Most Students spend most of their time with their friends at school, build relationships with others, and form a group. However, they sometimes don\'t speak their minds clearly or make troubles due to wrong communication. The purpose of this study was to develop a classroom-based nonviolent communication training program, run the program for middle school student, and identify the effect on improvement in their communication and peer relationships. As a result, experimental group with classroom-based nonviolent communication training program improved more than control group in their communication and peer relationships. The major results of this study are as follows: First, it is significant to develop a classroom-based nonviolent communication training program. There is not only a lack of previous research, but also is much to be desired on communication program which enables the whole classroom with ordinary students to be discretionary, although group counseling for elementary students or university students, adults has been supplied. Second, this result, which the program has an effect on improvement in their communication and peer relationships, can apply to prevent recent school problems including school violence and bullying. Because most of adolescents\' problems are caused by lack of communication skills to identify what are needs of others and speak their minds. If interpersonal skills program using creative discretion or classroom meeting is applied, the occurrence of inter-peer problems due to wrong communication would decrease and help us prevent adolescents\' problems. In conclusion, this program can apply to effective and instructive method for improving students\' communication and peer relationship in school education.