In this paper, I considered about a sign of thematic unit. In this case, I focused on Takashi Hasegawa. His theory is starting point of thematic unit in Japan. He had an awareness of the issues that is unreasonable skill principle in Japanese language education those days. As the correspondence, he advocated of thematic theory. I show three main points of this theory below. (1) “theme” is recognition theme and form of a question. (2) “Theme” must be decided intentionally. (3) Language activities must be set up effectively for approaching “theme”. His theory was practiced at the junior high school of Ehime University Faculty of Education around 1971. His theory was inherited by Chikako Makimoto who was teached by Takashi Hasegawa at Hyogo University of Teacher Education. His theory is was very influential in Japanese language education.