The guarding system of the \"Choson\" era is completed by the Gyeongguk-daejeon(an administrative canon) at the kings \"Sejong\" and \"Yejong\", and it is supplemented at the King \"Seongjong\". Excellent soldiers are selected under the provisions of the canon, and they are organized into the \"Geum-gun\" who guards the king and the \"Jungang-gun\" who takes charge of the capital defense and the royal family guard, with this, the guarding system for royal families is established. \"Geum-gun\" is composed of \"Naegeum-wi\", Gyeombok-sa\", Wirim-wi\" and Jeongro-wi\" in the period before the Japanese Aggression of Korea in 1952, and in the period after the aggression war, the organization of the \"Geum-gun\" is changed repeatedly according to circumstances in the period after the aggression. They(\"Geum-gun\") devote themselves to the protection of kings and the capital defense in the first period of the \"Choson\" era. But, in the circumstances of Japanese and Chinese aggressions, they perform their original duties wars to defend the country, and the role of \"Bibyeon-sa, a temporarily organized troops, is extended, and the military system is changed under influence of the wars. The most important change of the \"Geum-gun\" is the practice of five military units system, three military units of them, \"Hunryeon-dogam, Eoyeong-cheong and Geumwi-yeong, take charge of the guard of kings and the capital defense, and \"Chongyung-cheong\" and \"Sueo-cheong\" take charge of the defense of the outer areas of the capital region with key positions located at \"Namhan-sanseong\" and \"Bukhan-sanseong\"(mountain fortress Walls). The function of the \"Geum-gun\" is extended through the aggressions, therefore the number of soldiers is increased greatly. The guarding system for the country and its royal family is frequently changed according to the improvement of the people\'s position with themselves-awakening and their understanding of realities. But, the old system is remained, and so the number of soldiers in name only is increased. The reorganization of the \"Geum-gun including \"Howi-cheong\", \"Geumgun-cheong\", Sukwi-so\" and \"Jangyong-yeong\" is unavoidable to strengthen the royal rights that are weaken by deposing the king \"Injo\". The standing of the existing organizations is changed many times with financial problems. The enthronement of the king \"Jeongjo\" is a great epoch in the change of the guarding system. \"Jeongjo\" establishes the \"Sukwi-so\" and strengthens the \"Jangyong-yeong\" to destroy relatives\' influence and to practise new politics, and he strengthens royal rights while he is on the throne.