The argument of Constitutional Monarchy only circulated in Korea after the opening of the country’s ports (in 1876), and before Joseon’s sovereignty was stripped and the Korean peninsula was annexed by the Japanese imperialism in 1910. It was an argument that captures the very essence of Korean modern discourse on political reforms.BR Examined in this article is the argument of Constitutional Monarchy by Yu Kil-chun, who supported the idea of enlightenment and led political changes during the Gabo-year Reform, using recently found sources of information, and with the concept of “Monarchical-Constitutional System” in mind. One of the newly found sources is the Houses of Parliament Act(院法), which he designed based on his ideas regarding the National Assembly, that he had developed during his asylum in Japan when he honed his own plans for Korean domestic reforms. And the other is Kilsa-weon Regulations(吉士院規則), which was a set of rules for the Kilsa-weon chamber. Meanwhile, the aforementioned “Monarchical-Constitutional System” is an idea inspired by recent European constitutional historical studies, which chose to conceptualize the constitutionalism of certain 19th century European states, where the monarch was equipped with more power than the national assembly and took the lead in governance, as Monarchical-Constitutionalism.BR Examination of the Houses of Parliament Act(院法) and the Kilsa-weon Regulations(吉士院規則) revealed that Yu Kil-chun was designing a Monarchical Constitutional System in which the monarch would have full control of the government and the government could restrict the National assembly’s autonomous functions. This was a vision different from similar cases either seen in Preussen or Japan, as both countries were Monarchical Constitutional States in the 19th century’s latter half, but constitutionally separated the Government and Assembly from each other. Then again, compared to those two cases, Yu Kil-chun’s idea was to have the king wield lesser power in his governance, but the government on the contrary maintain a higher status, which I believe was his own way to put both the monarch and the national assembly in check in an overlapping fashion. In such circumstances, where the monarch and assembly are both checked, national governance would have to be helmed by governmental officials, in other words the bureaucrats. It seems Yu Kil-chun was designing a Monarchical Constitutional system led by officials of the government.