This paper deals with the Fugen-san 普賢讃, one of the parts of the Hokke Senbō 法華懺法performed in the Shunie ceremony 修二会 at the Nigatsu-do Hall of the Todaiji 東大寺二月堂. The Fugen-san consists of sixteen verses, and can be found in the Dasheng bensheng xindiguan jing 大乗本生心地観経. However, the texts of this sūtra nowhere mention the term fugen, and it is not clear why the Fugen-san is so called. To find the origin of the name, this paper examines the ideological content of the Dasheng bensheng xindiguan jing. This sūtra was considered important by Tendai scholars such as Annen 安然, Ryōgen 良源and Genshin 源信, and it is regarded as having the same meaning as the Guan puxian pusa xingfa jing 観普賢菩薩行法経. Therefore, this paper argues that an ideological factor may have influenced the origin of the name.