The purpose of this paper is to examine, in terms of Wittgenstein Philosophy, the concept of joint attention that is endorsed by Jerome Seymour Bruner and Michael Tomasello. Bruner and Tomasello appreciate the problem of indeterminacy of reference suggested by Wittgenstein's notion of ostensive definition and family resemblances. They insist that the concept of joint attention is crucial to solve the problem. However, the concept can be criticized for not considering two points. (1) It fails to see that intentions emerge ex post facto because it presupposes a substantive view of intention. (2) It also fails to recognize that intentions emerge in a certain context. In conclusion, this paper points out that the concept of joint attention need to be examined by Wittgenstein's considerations of intention.