Imun is the official style of writing that has been used since the Yuan Dynasty period. Our country concentrated on educating talented individuals of Imun in order to form an exchange relationship with China. Thus, during the Joseon Dynasty, the government appointed a variety of Chwijaeseo in order to acquire and select talented individuals of Imun. If looked into the separated categorizations of the Chwijaeseo, the Confucian scripture holds the most important position; aside from that, it consists of diverse reference books such as category of Lawbook, category of history book, Collection of Ancient Events, diplomatic documents for China, Chinese Phrase Book. In particular, the reference books Ihakchinam and Sengcayhyokyeng take distinctive positions. The Ihakchinam lists and translates administrative and legal terms once used in China back at that time. It also lists the virtues and exemplary cases that government officials needed to possess, along with moral cases that showed the miserable end of cruel government officials. Therefore, Ihakchinam not only holds the purpose in language acquisition, but also educates the meaning of the responsibilities of government officials. For these reasons, this reference book is one of the most appropriate materials to acquire Imun. Sengcayhyokyeng is the translated version of the Confucian scripture called hyokyeng and it is translated in Mongmwuncikyekchey, which is the Chinese language that was used during the Yuan Dynasty. The Sengcayhyokyeng is also appointed as an important study material of Imun. Although Imun is rooted from traditional Chinese characters, the vocabulary and grammar is mainly composed of Wondaehaneo, which is a language influenced by both the distinct characteristics of the official writing style and the Mongolian language. Therefore, ever since the Goryeo Dynasty, specialized institutions, such as Ihaktogam, were built for Imun education. During the Joseon Dynasty, Hanigwa was built for the selection of talented Imun individuals. The government also appointed a variety of Chiwijaeseo to help with acquiring Imun and selecting talented individuals of Imun.