In "Kojiki" and "Nihonshoki" the successive emperors from Jinmu (神武) to Suiko (推古) or Jito (持統) are recorded. By the late investigations it was proved that the emperors after the Emperor Ojin (応神) really existed, but there are still doubts as to the existence of the emperors before him (Ojin). Some people said that the possibility of the existence would go back to the Emperor Sujin (崇神), but this consideration was induced only by the internal criticism of "Kojiki" and "Nihonshoki". In order to clarify its evidence, the careful examining by means of the materials besides the above two books will be necessary. Accordingly, in this article, I picked up "Joguki-ichiiu" (上宮記一云), which the historians have hitherto overlooked, and correcting the misunderstandings in reading it, I could prove the time when "Joguki-ichiiu" was written is some time before "Kojiki" and "Nihonsohki" were compiled. Then, by comparing the containing articles with those of "Kojiki" and "Nihonshoki", I examined the reliabilities of the historical facts of them. These facts can suitably be located in the place of the history of the Yamato Dynasty conceived by the aid of foreign materials, (that is, of China and Korea) and the studies of archaeology. In this critical way, it is able to say that the real existence of the Emperors, Sujin (崇神), Suinin (垂仁) and Keiko (景行), in the time of the foundation of the Yamato Dynasty, has got verification.