The broad purpose of this article is two-fold: first, to grasp a general picture of a research trend on teacher educators’ professional development which addresses their roles, functions, expertise and models of professional development for teacher educators; and second, to forward the idea of applicability of the Lesson Study as a model of teacher educators’ professional development in developing countries’ contexts, through examining a joint project having been conducted between Hiroshima University and Dominican Republic from 2010 to 2015. The article shows that special considerations are needed when a teacher educators’ professional development is carried out in these countries, which is derived from its progress of upgrading teacher education from normal schools level to university level. Also, it was found out that the Lesson Study itself could hardly have effects on improving the teaching practices without institutional support and individual teachers’ readiness toward lesson analysis, which is differ from Japanese context.