Through the analysis of Manyōdaisyōki 『万葉代匠記』, the commentary on Manyōshū 『万葉集』, this article considers an aspect of the studies of Keichu 契沖 (1640-1701) , one of the most famous scholars of Japanese classical culture during the early Tokugawa period. Section 1 of the article explores Keichu's views on Japanese poetry, which he thought was a response to feelings aroused by innumerable events. And on this count, exclusively influenced by medieval poetics in Japan, he insisted that Japanese poetry resembled Chinese poetry. Through analysis of the Manyōdaisyōki introduction, Section 2 elucidates the originality of Keichu's views of Manyōshū, summarized into two major points: First, Keichu thought that Manyōshū was comparable to Shi jing 『詩経』, one of the classical Chinese texts. Second, he believed that Manyōshū had the same effect as Shi jing, that is, making each reader gentle. Section 3 delves into this issue in greater detail, clarifying that Keichu regarded Manyōshū as politically useful. Section 4 examines some of Keichu's commentaries on Manyōshū to consider their characteristics: Because his study of historical documents and classical Chinese texts enables him to gain a clear, detailed understanding of these poems, he found that they expressed standards and reason. This article's analysis derives the following conclusion. A major characteristic of Keichu's commentary on Manyōshū was digging out its precepts. Futhermore, from this study, I deduce that Keichu's commentary on the love poems of the nobles who understood the norm of Confucianism's standards contained his notions about human beings.