Abstract: As many scholars have pointed out, the Collected Works of DU Fu, which originally spread to Japan in one complete volume, is very likely to be the two-volume set titled "Du Yuanwai Ji" brought back by Ennin when he returned to Japan in Jōwa 14(847, the first year of the Tang Dynasty under the reign title of Dazhong). Based on this, and taking into account the context of BAI Juyi's greatest fame in East Asia from the tenth to thirteenth centuries, this paper analyzes the historical materials and points out the reasons why "Du Yuanwai Ji", which Ennin had copied with great difficulty, was not included in Nihonkoku genzaisho mokuroku. This is closely related not only to the fierce conflict between the ambassador and vice-ambassador of Japanese Diplomatic Mission to Tang dynasty China, but also to the fact that the nobles and literati led by the emperor showed fervent enthusiasm for BAI Juyi's poems and the appearance of Baishi Wenji in Nanchan Temple copied by Egaku. However, this situation changed in the late Heian period and even the middle Kamakura period when annotated versions of "Du Gongbu Ji" by WANG Zhu and "Jizhu Du Shi" by GUO Zhida were introduced into Japan. This finally secured a place for DU's poetry and essays in the political and literary circles of the middle ages in Japan, and also played a role in bringing the subsequent trend of honoring DU Fu among the the Five Mountain Zen Temples.