In this paper, I studied the appendix of letter writing guidebooks that were used from the late Joseon Dynasty to the 1950s. This period is divided into four periods, namely the late Joseon Dynasty, 1890s~1910s(period of growth), 1920s and 30s(period of prosperity), 1940s and 50s(period of decline). Among the letter writing guidebooks from the late Joseon Dynasty, 『Gandokjeongyo(簡牘精要)』 treated the appendix importantly. In addition, the part of an appendix to 『Gandokjeongyo』 also appeared in appendix of modern letter writing guidebooks, that is to say ‘Formal designation between family and relative(三黨稱呼)’, ‘a letter to the marriage(婚書式)’, ‘a message that inform a person's death(訃告)’, ‘a letter that comforts death(吊狀)’, ‘a letter of consolation(慰狀)’, ‘the old name of each village’. As a result of studying the appendix of the letter writing guidebooks in the 1890s~1910s(period of growth), it was divided into the aspect of inheriting the late Joseon Dynasty and the aspect that reflects the new changes of the times. As a result of studying the appendix of the letter-writing guidebooks in the 1920s and 30s(period of prosperity), things related to weddings(婚禮)·funeral(喪禮)·ancestral ritual formalities(祭禮) were becoming a trend. this reflects the public's desire to pretend to be a noble while making Confucian customs a part of their daily lives at a time when status and class collapsed. on the one hand, the method of writing telegram and postcards, which were not seen in the appendix of the previous period, and what can be called a kind of life encyclopedia appeared in the appendix. in addition, the East-West chronology is included in the appendix of many letter writing guidebooks during this period, indicating that letter-writing guidebooks tend to become manneristic. As a result of studying the appendix of the letter-writing guidebooks in the 1940s and 50s(period of decline), it was difficult to find the general characteristics of the appendix only during this period. however, I was able to find the uniqueness of individual letter-writing guidebooks. As such, it can be seen that the appendix of the letter-writing guidebooks continued to change until the 1950s in line with the trend of the times while absorbing new phenomena while inheriting the tradition.