The “Sandai-Sōron” is a case held by the Eihei-ji community involving the Kamakura shogunate; the battle of succession between Tettsū Gikai and Gien arose after their master Dōgen died, and concerned the question of which of them was suitable to be the third abbot of the Eiheiji. The seven sources extant describe the incident differently, however, the records contain various problems, and the historical facts are unclear. In former studies, the Hōkyō-yuishoki had been considered the oldest document that speaks of the “Sandai-Sōron.” Recent research indicates however that the Hōkyō-yuishoki was written after the Edo period. Here, I explicate the year of creation of the Hōkyō-yuishoki, as well as specify the year of creation of the entry on the “Sandai-Sōron” in the text, putting it between 1615 and 1688. I do so by comparing it to the Keigagyōjitsushuroku owned by the Tanimura Bunko in Kyoto University.