As the preliminary-consideration class law on operation of the class law in the early Joseon dynasty is aimed to basically prescribe the absolute upper and lower relations among classes inside the army, it belonged to the martial law in the broad range. In particular, it played a role of preventing official discipline from being destroyed because authority as a higher officer drops, by which a lower-grade personnel despises an upper-grade personnel. Due to this, there was the time that newly consolidates and operates this in order to establish a system in the upper-and-lower discipline and command by organizing the military power, which was scattered owing to several reasons, again into the army of having a king as the top. By the way, in the early Joseon dynasty, the extensive reform was driven over the whole of a military system in order to overcome confusion, which had occurred in the previous period. Out of those things, the attempt was also included in order to remove private-soldier elements, which had caused serious confusion before, and to re-organize it into a public-soldier system. Naturally, as one of fundamental laws for solution of problem, the introduction of a class law came to be examined. A person, who took the lead in introducing the class law in the early days of foundation in Joseon, was Jeong Do-jeon(鄭道傳). He made a law that the lower-grade personnel thoroughly obeys the higher-grade personnel unconditionally in the face of the first place without considering a social standing, birth, and background. And, he recorded this law in『Gyeongjeyukjeon(經濟六典)』, which is the first written statute in Ioseon dynasty. However, as the camp of King Taejong became powerful owing to the reshuffle of political circles, the direction of reorganizing the military system was greatly changed. In case of the class law, first of all, it made it a rule to apply literally. Some days later, he restored Ho-gun-bang(護軍房), which is the martial-duty class system in Goryeo, which had been the prior dynasty. In the wake of this, a person, who has good social standing, birth, and background as well as capability, was allowed to go up easily to the high position. There was mutually contradictory aspect between the provision of 『Gyeongjeyukjeon(經濟六典)』, which emphasized only class, and the system of the restored Ho-gun-bang. Owing to this, the basic principle of the class law, with saying that the one-digit class needs to be strict against the one-digit class, may be damaged, thus a situation was serious. With entering the period of King Sejong, the work was started that abolishes Ho-gun-bang(護軍房) and modifies and supplements the provision related to the class law of 『Gyeongje- yukjeon』. The work, which re-consolidates the class law, was driven in earnest along with compiling 『 Gyeong-guk-dae-jeon(經國大典)』. Finally, as the compiling work of 『Gyeong-guk-dae- jeon』 was completed, even the typical class law in Joseon dynasty came to be positioned. As a result, the period arrived when the upper- and-lower relations between classes are strictly prescribed on the basis of the written law.