The intent of the study was that reveal to effects of Family Art Therapy on the stress of mother and siblings of child with mental retardation. The purposes of this study were as follows: First, investigate the characteristics of the family(child with mental retardation. mother, siblings) reaction to Family Art Therapy. Second, manifest the effect of Family Art Therapy on the stress change of mother of child with menta] retardation. Third, reveal the effect of Family Art Therapy on the stress change of siblings of child with mental retardation. For this study, the Family Art Therapy program that can promote positive interaction was employed for child with mental retardation of 3 grade in special school for middle, mother and siblings. To observe the results of this study. the researcher qualitatively analyzed session activities of the Family Art Therapy program, and then watched characteristics in the response of child \vith mental retardation, his mother and siblings. and the characteristics of HTP(Honsc-Trcc-Pcrson)/KFIl(Kinclic Family Drawing)/KSD(Kinetic School Drawing) of Lhe family was analyzed Lo pre-Lest and post-test. And the changes of pre and post-test score was viewed by using stress scale for mother and siblings. The conclusions of this study were as follows : First, Family Art Therapy had have an influence on increasing attitude of positive change child with menta! retardation, mother, and siblings. Second, Family Art Therapy had product an influence on decreasing the stress in mother of child with mental retardation. Third, Family Art Therapy had exert an influence on decreasing the stress in siblings of mental retardation. Especially, child with menta1 rcLardation showed that the 1asting time of positive participation activities more long than that of initial session and reduced the frequency of talking to oneself, completed his task to a finish. In case of his mother, as more repeatedly session, exerted a positive support and reinforcement than those of initial session. Also in case siblings, as showing be on the decrease sense of denial when doing program v,rith together. Like that, child with mental retardation was getting better gradually in taking family's advice and doing program with family together. The relationship and interactions of the family(mother, siblings) were also getting better gradually. Based on this study, the following recommendations may be suggested: First, for further study, it is necessary to apply for other family members. Because this study was concerned ,vith mother and siblings, it is impossible to know about father. Second, in order to understand deeply interactions of family member, long tenm studies be acted.