<論説>「氏爵」の成立 : 儀式・奉仕・叙位

Abstract

氏爵というと一般に平安時代、毎年正月の垣例の叙位で、王・源・藤原・橘という当時有力な四氏の出身者が従五位下(叙爵) に預かることとされているが、この他、即位式・大嘗会といった天皇の「代替り」の儀式や「暦の代替り」ともいうべき朔旦冬至の儀にちなんで行われる叙位(即位叙位・大嘗会叙位、朔旦叙位) では、伴・佐伯・和気・百済王というもはや有力ではなくなった四氏の出身者に対しても叙爵(「氏爵」) が行われた。しかし、これらの「氏爵」については史料的制約もあり、殆ど研究が進展していない。本稿は伴氏以下四氏への「氏爵」について、その実態を検討し、「氏爵」の成立時期・成立理由について考察したものである。まず、「氏爵」の典型例を理解するため、応徳三年の即位叙位について、百済王氏の「氏爵」申文と『通俊卿記』を通して理解を深めた後、そこで得た理解をもとに、即位叙位全体、更に、大嘗会叙位・朔旦叙位に検討を及ぼし、「氏爵」の成立時期を九世紀後半から十世紀初め頃に求めた。また、その成立の由来は、天武系から天智系へと皇統が変化した光仁・桓武朝における、「代替り」の儀式への奉仕や「功臣」と称されるような先祖の天皇家への功労に淵源をもち、それに対する反対給付的なものであると同時に、これら四氏が没落するに随い、「氏爵」の授与には、「代替り」の儀式に奉仕したり由来の深かった氏の維持・継承やそれらの儀式に関連した行事の継続のため、という側面も生じたことを指摘した。

Ujinoshaku has generally been thought to be a practice in the Heian period that could be found in the regular January investitures that conferred court rank of ju-goi-ge 従五位下 (joshaku 叙爵) upon the children of the four influential families of that time, namely, O 王, Minamoto 源, Fujiwara 藤原, and Tachibana 橘. Yet, in the case of the Investitures connected with the ceremonies of imperial succession such as the coronation or daijo-e 大嘗会, and of sakutan-toji 朔旦冬至 which could in a way be interpreted as "succession of callendars", the same rank was conferred upon the children of the four effete families, namely, Tomo 伴, Saeki 佐伯, Wake 和気 and Kudarao 百済王. As to the second type of ujinoshaku practice, hardly any meaningful resarch has been done, due to the limitations of the records. This article, by analyzing the actual conditions of the second type of cenferment, tries to ascertain the time and the background of its formation. First, we examined two historical documents : moshibumi 申文 of the Kudarao family by which they applied for conferments, and Michitoshi-kyo-ki 通俊卿記 the Diary of Michitoshi. Both them were related to the investitures made on the occasion of the coronation in the third year of Otoku 応徳. Through this inquiry, we were able to extract a typical case of the practice. Then, we spread our scope of analysis to take into consideration the investitures at daijo-e and sakutan-toji. In conclusion, the date of the formation of the practice should be set between the latter half of the 9th century and the beginning of the 10th century. In addition, we pointed out the fact that the practice came about in consideration of the services that were done by the ancestors of the four families during the reigns of Konin 光仁 and Kanmu 桓武, when the imperial lineage had changed from the Tenmu 天武 line to the Tenchi 天智 line. The ancestors had served in the ceremonies of "succession" and made such distinguished contributions to the imperial family as to be called koshin 功臣. Although these four families declined in the course of time, they continued to serve in the imperial ceremonies, as their attendance was still necessary for the proper execution of the ceremonial functions. Thus, the ujinoshaku practice came to be utilized for preserving the lineages of these families.