Recently, the mechanism of communication deficits in autistic children has been argued from various theoretical background, such as "cognitive theory (Theoryof mind)", "affective theory," and "affordance theory." Most studies consider the joint attention to be a precursor of communication skill. We can realize well functioning speech or reciprocal communication in a social context, when both the speaker and the listener have common affective states or mind shared with one another. Then, how can human being develop the ability to have affective states or joint attention? The author proposes "body-experience sharing theory (BEST) ." This theory insists on the importance of sharing body-experience or reciprocal communication through body sensation such as warmth and softness, as the premise for developing affect sharing and joint attention. Based on the shared good body-experience with caregivers, children come to be able to get into a world in which common meaning is shared. In this article, the author suggests that the disturbance of shared body-experience causes joint attention deficits in autistic children, and discusses the BEST based intervention strategy of developing joint attention.