The Korean linguist who said ‘Hangul is my life,’ Oesol Choi Hyun-bae’s (1894~1970) posthumous complete collection has been published. The publication was made possible thanks to the co-work of four years by Yonsei University Press and Oesolhoe (Oesol Academy), as part of the Yonsei University 125th Anniversary Memorial Project. Comprised of 28 books, the collection includes Oesol’s handwritten manuscripts of ‘Urimalbon,’ ‘Chosunminjokgaengsaenguido,’ and ‘Hangulgal,’ other printed versions, and articles that were published in the opinion section of newspapers. Unlike earlier ones, this recent collection contains a whole series of his work, from Oesol’s very first manuscript to his last printed work. This feature enables the readers to examine the changes in his thinking over the years. His studies in Hangul, or the Korean language, started at Ju Si-gyeong’s Korean Language Institute, and proceeded throughout the Japanese Colonial Era. At this period, he contended that not losing Hangul was the way to get back the country from Japan. He was a professor at Yonhi College until 1937 when he was forced to resign, and in 1941 he was imprisoned on charge of an incident as a member of the Korean Language Association. He was released when the country was liberated in 1945, and administered textbook publication as the director of the Textbook Compilation Bureau of the Ministry of Education. In 1962, he received the Order of Merit for National Foundation in recognition of his contribution to the research on Korean grammar and the Korean Language Movement. After his death in 1970, he was posthumously awarded the Order of Civil Merit, Rose of Sharon Medal.