This study is to investigate the change of an autistic student`s stereotype behaviors by participation in a dance therapy program that was developed by modification of basic motions of the ballet. The main focus of this study is to show how the autistic student`s stereotypical behaviors change by following the 4 steps of a dance therapy program. This study is conducted by using the A-B-A` technique of a single subject research method. Changes of the sample`s stereotypical behaviors were measured in the pre-test, main-test, and post-test sessions. And collected data was analyzed by a graph. Kim`s dance therapy program is constructed in 4 stages-step to decrease his stereotypies. The 4 stages of the program are 1) mimic-session; 2) motion correction; 3) adjust to music; 4) stereotype behavior correction. Kim participated in the program with 11 peers who are mentally retarded(TMR). The results of this study indicates that Kim`s stereotypical behaviors were changed by following each steps of the dance therapy program. The results also indicates significant differences between the pre-test and post-test assessments [t(14)=2.41, p=0.03]. To verify effects of sub-sessions of Kim`s dance therapy program, a `one-way ANOVA test` was employed. However, there is no evidence that indicates significant statistical effect of sub-sessions[F(3,26)=0.87, p=0.46]. The result of the statistics does not mean that the program is not effective in changing Kim`s stereotypical behaviors, but means that Kim`s behavior did not dramatically changed in any sub-session.