Pope Pius Ⅱ(1458∼1464) was a well known humanist, also famous as a poet and orator. In 1462 he began writing Commentaries, a memoire of his life and work as a Pope. The title and structure of the book was derived from the ancient genre of Commentarii, which was the Italian literary trend of the Renaissance era. Scholars usually regard the Commentaries as “the only autobiography ever written by a reigning Pope” and also focus on the book`s political propagandistic character, similar to that of the ancient genre Commentarii. However, to fully understand the Commentaries, an approach in the direction of the author needs to be made. This means that to fully understand the historical context of the Commentaries, one needs to consider Pius Ⅱ`s personal life and the situation of the Fifteenth-century Christendom under the Ottoman invasions. The ‘anxiety’ which sprang from the conflict between Pius Ⅱ`s old universalism ideal and the awareness of the Papal authority failing, was an important factor in why this book was written. This study focuses on the ‘apologia’ character of the Commentaries, which aims to defend Pius Ⅱ`s failures in the crusading policies in the earlier years of his reign. His own description of his youth, conclave of 1458 and early years of his reign in Commentaries are further discussed. Nevertheless, Commentaries does not really concern itself with historical preciseness. Rather, how Pius Ⅱ reconstitutes historical facts to defend himself was one important point of this study. Pius Ⅱ selected certain facts and reorganized them in such a fashion to favorably describe his life and his work. This study argues that Pius Ⅱ wrote his book with readers in mind, and that the Commentaries is a result of his awareness of the public`s eye.