Due to the increase in general life expectancy, the adulthood of people with intellectual disabilities is gradually getting longer as well. However, there is a lack of appropriate education or rehabilitation for them. In particular, there is little training available for them to improve their communication and socialization skills, which are essential for adults with intellectual disabilities to live as members of modern society. Accordingly, the purpose of this study is to analyze the effects of therapeutic horseback riding on the communication and socialization abilities of adults with intellectual disabilities. To conduct this study, the pretest-posttest control group design was used. The experimental group and the control group consisted of 20 adults with intellectual disabilities, respectively, and tests for communication and socialization abilities were conducted, and only the experimental group was allowed to participate in the therapeutic horseback riding program. The experimental group was to take 16 therapeutic horseback riding sessions for 8 weeks. For statistical processing in this study, the homogeneity between the experimental group and the control group was tested. And the pre-tests and post-tests of the experimental group and the control group were analyzed to measure the effect of therapeutic horseback riding on the communication and socialization abilities of adults with intellectual disabilities. The results of this study are as follows. The experimental group and control group designed in this study, when analyzed, showed homogeneity. It was confirmed that the experimental group that participated in the therapeutic horseback riding program showed significant improvement in their communication and socialization ability scores compared to the control group that did not participate in it. Based on these research results, this study suggested the need to plan a systematic therapeutic horseback riding program and expand participation opportunities so that it can help adults with intellectual disabilities improve their communication and socialization abilities.