4 royal palaces are currently remained from capital city (Seoul) of 'Cho-Sun(朝鮮)' period. In these palaces, 'Main hall of Royal Palace(正殿)' is the center of the Royal Palaces. The 'Main hall of Royal Palace' of the Royal Palace was the best building of that time. Therefore there were many studies about the 'Main hall of Royal Palace'. But these studies were individual studies of these 'Main hall of Royal Palace'. Therefore, this study is to analyze and compare 4 'Main hall of Royal Palace' of the Royal palaces. It is to study the proportion regarding the Diameter of the pillar, the Height, the pillar and pillar Interval's Distance, and the arrangement of 'Kong-Po(bracket sets)'. With these studies, it is to prove that the 'Main hall of Royal Palace' is the building which high construction technique of this time is expressed. Result of this study is as followings; First, the proportion of pillar height(H) to its diameter(D) average from H=8.0 to 8.5D. Only the Myeong-Jeong-Jeon omitted the 'Go-Ju(高柱)' in the 'Toi-Kan (退間)' to place Ea-Jwa(御座). Second, Second, the proportion of diameter of the pillar of 'Eoi-Bu-Pyeong-Ju(外部平柱)' and 'Nae-Jin-Go-Ju(內陣高柱)' average D1(Diameter of 'Eoi-Bu-Pyeong-Ju') =0.91D2 (Diameter of 'Nae-Jin-Go-Ju'). In regards to the height, the single floor 'Main hall of Royal Palace' and double floor 'Main hall of Royal Palace' seems to be different. The height proportion of the double floor 'Main hall of royal palace' is H1(Height of 'Eoi-Bu-Pyeong-Ju')=0.34H2(Height of 'Nae-Jin-Go-Ju') and single floor 'Main hall of Royal Palace' has a proportion of H1=0.62H2. Third, in Geun-Jeong-Jeon, with the proportion of height and diameter of the pillar, interval's distance between pillars and diameter, the pillar interval distance and height, of 'Ea-kan(御間)' from the 'Toi-Kan' is different from 'Main hall of Royal Palace'. This is because the structure of 'Toi-Kan' of Geun-Jeong-Jeon is not stable. In order to reinforce this, 'Gui-Go-Ju(隅高柱)' of the Geun-Jeong-Jeon jut out $4{\sim}7%$ more compared to In-Jeong-Jeon. Fourth, when comparing double floor 'Main hall of royal palace' of Geun-Jeong-Jeon and In-Jeong-Jeon, based on distance of 'Eoi-Bu-Pyeong-Ju' and 'Nae-Jin-Go-Ju' of lower level, the 'Sang-Bu-Pyeong-Ju(上部平柱)' of Geun-Jeong-Jeon jut out $4{\sim}7%$ more compared to the In-Jeong-Jeon and also It becomes thicker. Fifth, the arrangement of 'Kong-Po' on the front row of 'Gan(間)' had to do with the change of side 'Gan'. Even though the Geun-Jeong-Jeon and the In-Jeong-Jeon were double floors, the arrangement of the 'Kong-Po' is different because the number of side bay is different.

This study is to comprehend the interior space of the Royal Palace in the 15th Century, the early years of Joseon Dynasty. The subject of this study is limited to the center of the Royal Palace, that is Jeongjeon(正殿, the royal audience chamber) and Haengrang(行廊, which encloses Jeongjeon on four sides and has many rooms). It is very important to understand the usage of the interior space because the architectural space consists of the space unified by the organic function of the interior and the exterior space. But there are few studies on the interior space of Jeongjeon and Haengrang at the Royal Palace. Therefore, the purpose of this study is to understand the interior space of those buildings. The result of this study is following. Haengrang has several uses such as a night duty room, a storehouse, a government office or a banquet hall etc. So the interior spaces were finished with various methods that were suitable for the use of each room, and the material of the floor were the ground, Maru(the wooden floor) or Ondol(the Korean traditional heating system) There were held many kinds of ceremonies in Jeongjeon, and the government officials could not enter the inside of that building and took part in the ceremony on the front court of Jeongjeon, except the men performing the ceremony. But the high ranking officials could enter the inside when King gave a banquet and there, they prostrated themselves before King. They sat down with their legs crossed on the ground floor instead of sitting on a chair. When King held tea ceremony with Chinese envoys in Jeongjeon, they sat on Gyoui(交倚, a kind of armchair). Then, the government officials performing the ceremony in Jeongjeon prostrated himself around the King and the Chinese envoys and others stood around them.

In order to reveal the source of the architectural norm embodied in the first built-form of ChongMyo's Main Building, three analytic types were introduced into research. According to the level of accepting the architectural form of ChongMyo in the Koryo Dynasty, these types were defined by 'newly interpreted form', 'newly introduced form', and 'coventionally accepted form'. Among the first built-form in ChongMyo's Main Building, the form of 'TaeSil' was newly interpreted on the basis of the Tang's realating norm, and the form of 'HyupSil' was newly introduced according to the contemporary trend that had increasingly regarded it as an indispensible form. But the form of 'IkSil' had the different source, that is, the architectural form of ChongMyo in the Koryo Dynasty. After reconstructed by the King ChungSun, that form had been sustained without any change until the end of Koryo Dynasty. In result, that form had been accepted conventionally at the first time of building ChongMyo in the ChoSon dynasty.