The purpose of this study is to investigate the differences in non-verbal communication behaviors between adults with intellectual disabilities and normal adults with the matched language age. The subjects were 20 adults with intellectual disabilities and 20 normal adults with the matched language age. The results of this study were as follows: in comparison of non-verbal communication behaviors between adult group with intellectual disabilities and normal adult group, positive non-verbal communication behaviors showed that the average number of adults with intellectual disabilities was higher in the order of eye movements> facial expressions> whole body. According to the results of this study, the group of adults with intellectual disabilities showed more positive non-verbal communication behaviors that meet the other s eyes during conversation. In dual meaning and negative nonverbal communication behaviors, adult group of intellectual disabilities showed behaviors that interfere with conversation situation in the order of negative eye movements> upper limb movements> lower limb movements> whole body> mouth movements. These results were analyzed as behavioral characteristics that appeared when there was a loss of concentration or difficulty in maintaining the topic in conversation situations. Therefore, in order for non-verbal communication behaviors of people with intellectual disabilities to become clearer means of communication, it is necessary for teachers and rehabilitation therapists to teach them to reduce dual meaning and negative non-verbal communication behaviors, and to use more positive non-verbal communication behaviors.