本稿は白河藩第三代藩主にして、幕府老中首座を務め寛政の改革を主導した松平定信(一七五八~一八二九)の晩年における文事、とりわけ定信自身が「細写」と呼ぶ、主として豆本形態での歌書の写本製作活動の総体的把握を目指したものである。まず桑名市博物館所蔵のものを中心とする定信作製の細写本二十八点(現存未詳のものも含む)について整理を試み、適宜書誌解題を付した。続いて、定信が筆写した書物がほぼ歌書に限られていることから、歌書製作の伝統的様式としての豆本形態について概観した。更に、定信自身がこうした細写本製作をどのようなものとして捉えていたのかについて、定信の抱いていた文学観の検証と併せて、定信自身の言説と行動とのあいだに見られる落差や不整合に着目しながら一定の解釈を試みた。その結果、定信はつまるところ当時の倫理観とは相容れない要素を含み持つ王朝文学の風雅な世界を愛好しつつも、あくまで治者として係累や周囲のひとびとに自己を道徳的に見せようと心を砕いており、その結果として、一見すると矛盾や強弁にも見える言動を行っていたものと結論付けた。This article aims at a comprehensive understanding of the elaboration of the Kasho (Waka book) manuscripts by Matsudaira Sadanobu (1788 -1829), a daimyō of the Shirakawa Domain who served as chief of the council of Elders of the Bakufu and led the Kansei Reforms. Among his writings in the later years, we put weight on ones in the mame-bon (miniature book) style which Sadanobu called saisha (minutely written). First we organized 28 of the saisha manuscripts made by Sadanobu, mainly of the Kuwana City Museum collection (including extant unidentified ones), and attached bibliographical information when necessary. Subsequently, we reviewed the mame-bon style as a traditional style of kasho manuscript making since books handwritten by Sadanobu are almost limited to kasho.We tried to obtain certain interpretation on Sadanobu's perspective toward the roles the manuscript making played in literature together with the validation of Sadanobu's view of literature, while paying attention to differences and or inconsistencies between Sadanobu's discourse and his behavior. We concluded that contradictions and or bullish claims might have been seen in his behavior due to the differences between his duties and his personal preferences. Specifically, Sadanobu had to represent himself morally as the ruler to his dependents and to people surrounding him while he loved the elegant world of dynasty literature which had incompatible elements with the ethics of the time.