The term ESD (Education for Sustainable Development) is becoming popular all over the world, particularly in Japan. It is said that education is essential to sustainable development. Today’s education is crucial to the ability of present and future leaders and citizens to create solutions to contemporary global environmental, societal and economic problems and find new paths to a better future (UNESCO). In Japan, the idea of ESD is promoted by the Ministry of Education with connecting to the Associated School Project called “UNESCO School.” Educational practices such as environmental education, energy education, international education, the World Heritage cultural education began to spread at schools. However, the fundamental discussion regarding the concept of ESD is not enough, so that teachers sometimes admit that the notion of ESD is staying unclear. In this paper, three basic factors, Development, Education, and Sustainability for ESD are critically examined in the literature and the related Websites. What was done here is a review of the materials and the indication of the problems. In the sense, this is just a memorandum, namely notes for further investigation. The following was pointed out: 1) The original point of ESD was about environmental problems. 2) Under the influence of DESD since 2005 which was promoted by Japan at the United Nations, the term ESD became popular among others like EfS (Education for Sustainability), ESF (Education for Sustainable Future), ESL (Education for Sustainable Living). Anyway, the basic idea is about the global issues. 3) The term ESD is not necessarily adequate, because it includes the ambiguous word “development.” The Japanese translation of development is also problematic. 4) The concept of ESD demands the philosophical consideration on “knowledge” and “intelligence.” 5) The fundamental significance of ESD is that it requires the innovation of the current system of school education.