The purpose of this study is to verify if music therapy activity has effectively worked on changing communication, motility, and sociality of the children who have developmental disability. Individual activity was conducted twice a week and group activity was conducted once a week. The change on the children through out these activities were analyzed by carrying out KISE development scale, SMS(Social Maturity Scale), behavior and music diagnostic scale, pre-test, post-test, follow-up test by observing record to find out the effect of them. For subject of this study, 4 children who have developmental disability were selected among the children who committed music therapy to D institute located at Dae-jeon metropolitan city and then individual activity was conducted twice a week and group activity was conducted once a week. As for the method of study and measurement, after grasping developmental stage of the children by implementing KISE development scale, music proper for those children were created and used, and behavior change in an individual and a group activity was analyzed by using 5 rating scale of observation record on the basis of KISE development scale test. As for a change of sociality in a group activity, a change of children was analyzed by using pre-test and post-test of social maturity. As for the communicative expression upon early music activity, they showed more music expression on nondirective language but as sessions were proceeded, they showed a change in behavior by paying attention to linguistic instructions. In the area of motility, the coordination ability such as hands-feet, eyes-musical instrument and a gaze at therapist etc. among music activity were unnatural but they showed a change that coordination was getting balanced. Each child improved in the area of sociality as well, but they showed reduction or increase in group activity compared to individual activity due to their temperament characteristics. For the conclusion through the results of study, the improvement of communication for self-recognition and interaction was achieved in music activity. Also, physical activity responded through musical stimulus, in other words, the movement of motility naturally got balanced and harmonized. In the area of sociality, children also showed a difference in individual and group activity due to their personal temperament characteristics, but overall they showed improvement. As for creative music applied to subject of this study, individual creative music was not used considering different extent of weakness and difference of each child, but it showed meaningful improvement in communication, motility and social skill of the children. It is considered that more improvement will be achieved when using individualized creative music in accordance with characteristics of the children.