We have developed some thematic units of Japanese language learning for senior high school students, and practiced them since 1997. Now many teachers are trying to develop new style units for "Comprehensive Learning" (Sogotekina Gakushu), though in many cases they can't produce excellent results. The reasons they have difficulty in developing some new type, and can't get expected results are as follows: 1) the relationships between the aims and contents of the existing school subjects, such as Japanese, or Social Studies and so on, and those of the new subject (Comprehensive Learning), 2) the new subject emphasizes "Learning by doing", or "Experiences". By this method, it is not easy to help students achieve specific abilities and knowledges systematically. To find a solution to these problems, we insist that the structures and functions of thematic units for Japanese language we have developed should be reevaluate. From the first, the structures of the units and characteristics of teaching materials of Japanese language as a school subject are thematic and comprehensive, though Japanese language teachers often have little understanding of it.