Since the Meiji era, a lesson study has worked in the elementary school teacher communities in Japan. Japanese lesson study, called jugyokenkyuu is a professional development process that Japanese teachers engage in to systematically examine their practice. However, because there is a national curriculum and this curriculum has the force of law, Japanese lesson study tends to focus on only teaching method. Even so, lesson study is accepted around the world as a good model for mathematics teacher education. In recent years, qualities that are required of teachers are distributed in two major compartments. One is personal abilities for living through that period of time. The other is abilities for getting along with people. Jugyokenkyuu will contribute to develop abilities for getting along with people, but it seems that jugyokenkyu will not contribute personal abilities for living through that period of time. For this reason, we should construct new lesson study in japan. For putting this into practice, we need to motivate teachers. In the current national curriculum in japan, there are content-free subjects of mathematics. Mathematics teacher should make a curriculum for a lesson. In conclusion, I suggest that new lesson study needs to aspire to becoming a research of curriculum development. And to do that, teachers had better utilize frameworks of Substantial Learning Environments by Wittmann (2001). In addition, for ensuring validity of research, it is useful for using the teaching experiment methodology.