This book introduces the achievements of dental anthropology research in Japan to the people in the world. It starts with the tooth morphology of the people in the Paleolithic Period about 20,000 years ago. Then it goes through Jomon Age and Yayoi Age when the admixture of the people happened. Here the difference of the tooth shape between those two human groups is emphasized. After these ages, Japanese teeth were not the same from age to age influenced by the environment. In the current age of Japan, topics such as third molar agenesis, change of eruption time of the first permanent teeth, mandibular torus, and high canine are discussed. These abnormal conditions in Japan also reflect the characteristic features of Japanese history and culture.