To promote multifunctional activity, it is crucial to clarify how jointness is formed in connection with farm structure. This paper examines the relationship between multifunctional activity and farm structure by focusing on the educational function of dairy farming, i.e., farming experience services, in Japan. The main findings were as follows. First, from our conceptual consideration we can say that the educational function is determined by technical and institutional jointness and there is a U-shaped relationship between farm diversification and provision of farming experience services. In addition, the national program aimed at promoting this educational function was effective in enhancing this function. Second, however, from the empirical evaluation farmers only partially internalize educational externalities by treating them as supplementary services combined with processed products. Therefore, appropriate integrated management of these newly emerging educational services to become a viable market should be fully addressed in the future, especially for family farms.