The autistic disorder has been known as a disorder that shows confined traits in the area of activities and interested fields, while showing some extraordinary development in the regions of social interaction and communication. The aim of this research is to propose a clinical approach for social welfare service by looking into how the horticultural therapy affects autistic children's isolative behaviors, escapement behaviors, and impetuous behaviors. I think that if social workers try to find out various approaches of this horticultural therapy, which has not yet been generally accepted, they can elevate the standard of their services as well as diversify the kinds of client services. In order to examine these research questions, this research examined the questions on the basis of a theoretical background concerning the horticultural therapy and the unadaptive behaviors of handicapped children with autism. The subject group consists of three children who were diagnosed as having some developmental disorders and who are currently attending a facility located in the city of G in Gyeongnam Province, specializing in handicapped children only. The research has focused on their unadaptive behaviors before and after the intervention with the horticultural therapy. The research covered a period from March 10, 2009 through April 10, 2009, during which ten times of experiments had been conducted with 40 minutes a day and twice--Tuesday and Friday--a week basis. In order to clearly observe the changes in unsociable activities, I have videotaped all the treatment sessions and measured these by way of the whole interval recording. I used the “multiple baseline designs” among the three subject children as a way of research. With the support of these conclusions, the research shows that as an intervention method with unadaptive behaviors, not only the existing approach from the therapeutic aspect but also the horticultural therapy by way of various natural objects we find in our daily life, will not only minimize the children's stress but also assist their development in cognitive, physical, and social aspects. I believe that by proving the effects of the horticultural therapy in the clinical scenes of social workers, who have a variety desires, we, social workers, can widen the utilities of the horticultural therapy and provide as well the basis that welfare facilities, children nurturing facilities, and clinics can experiment with this program.