Yoo Gil Joon(l856-1914) was one of the greatest educational thinkers of Korea. The purpose of this study is to research on his educational idea and to systemize his theory, and there by to contribute to, based on sound national orthodoxy, establish educational direction of Korea enabling to positively cope with the rapidly developing new civilization of the word. His fundamental idea on education was formulated from nationalism based on national legacy and orthodoxy. The gist of the results of this study on his thoughts are as follow 1) He emphasized the education which would establish national orthodoxy by way of encouraging the coincidence education of written and spoken language on the ground that the Korean letters identify with its language. 2) He classified the human behavior types responding to modernization as the host, the guest, the slave, the offender and the invalid of the modernization . The theory (in which he advocated for adopting the attitude of host of the modernization responding positively to the new civilization with the sprit of a pioneer and exploror) was the fundamental key note of his thought. 3) He held that the education ideal the nation and the society should pursue is a harmonized character with his intelligence, sentiment and will. His fundamental aim of education is to cultivate moral disposition of the character and to enrich the life through acquirement of knowledge and the technic necessary for living.