This paper is a review of the historical significance of Gansongbon(1940), the original copy of the Hunminjeongeum Haeryebon (Commentaries on the “The Correct Sounds for the Instruction of the People”)published in 1446 AD by King Sejong the Great. The exact account of the acquisition of Gansongbon was revealed in detail allowing the historical significance of that period to be made clear. With its registrationon UNESCO’s Memory of the World list in 1997 its significance was restored as its principal academic value was appraised according to the evaluation standards of the Memory of the World Programme. The first reason Gansongbon is historically significant is that it was protected during a period of hardship. Jeon Hyeong-pil’s purchase and possession of the Haeryebon at the beginning of 1940, the most dangerous period of the Japanese colonization of Korea, maintained the national pride of Korea and protected a cultural artifact of humanity. Secondly, by producing copies of the original and photoprints of the Haeryebonat the right time scholars could study them and reveal the academic value of the letters of Hunminjeongeum and the contents of the Haeryebon. Through the 1940 copies of the original, the 1946 Joseon Language Society photo prints, and the 1957 Tongmungwan photoprints, Gansong helped the research and communication onthe original copy and in 2015 his personal reproduction was released. Finally, the Gansongbon played a decisive role in bringing to ligh tthe historical value of King Sejong’s creation of Hangeul in 1443 and proclamation of it in 1446, as well as its historyof laborious development over 400 years. From the discovery of the Haeryebon the context of Hangeul’s creation and proclamation was revealed in full and the creating principle behind Hunminjeongeum and its historical value therein was able to be illuminated.