The congratulatory party that celebrated the 50th anniversary of the birth of King Sunjong took place at Injeongjeon Hall in Changdeokgung Palace on March 25, 1923, during the period of Japanese Occupation. As the royal family would not hold any big events after the demise of King Sunjong in 1926, it was the last event by which one can track changes in the parties of the Joseon Dynasty. This was different from the usual parties of Joseon Dynasty. The changes involved the venue, as it was not held at Jeongjeon (the courtyard for the main building) but instead took place inside Donghaenggak and Injeongjeon placed in the corner, and it also involved the serving luncheon and dinner, with participants seated at two rows of Western-style tables. Such changes distinguished the party from the previous Jinyeon (palatial party) of the Joseon Dynasty. Despite such changes in the royal ceremonies, in contrast to the Korean Empire, specific norms were not adopted in the period of Japanese Occupation. The modernizing changes to the ceremonies between the Korean Empire and the period of Japanese Occupation show how the Joseon tradition developed into the modern tradition. Presumably, there were changes to the music and dance used at the party, but details on such alterations cannot be found. At the event, eleven instrumental pieces－including Taepyeongchunjigok－and seven pieces of Mudong jeongjae (“court dance music with a boy dancer”) were performed. Instrumental music and Mudong jeongjae were presented at both luncheon and dinner. When Mudong jeongjae was performed at the party, it drew attention, as this represented a restoration of a presentation that had been removed from the royal protocol 20 or so years before. Moreover, the students of Yiwangjik aakbu (“Office of the Yi Dynasty’s Ceremonial Music”) were trained to perform for the event, which was significant in that has carried the tradition of Mudong jeongjae up to the present times. Having considered the performance of Mudong jeongjae following the 50th anniversary of King Sunjong’s birth, Yiwangjik aakbu performed in Kyoto. Moreover, having been performed at the Kyoto presentation, Jangsaengboyeonjimu was learned by a Japanese dancer. Based on this, Miyako Odori was created in Japan. The work was performed at the exposition that not only marked the participation in World Expo but also celebrated the marriage of Hirohito and the 15th anniversary of the Korea－Japan annexation. Aalthough Mudong jeongjae was restored for the 50th anniversary of King Sunjong’s birth, it was one of the projects that was presumably planned and prepared for such purposes. Despite its changes, the ceremonies during the period of Japanese Occupation, including the party that celebrated the 50th anniversary of King Sunjong’s birth, are highly significant in that they were crucial in carrying traditional Korean music up to the present times. Nevertheless, musicians’ strenuous efforts to carry the traditional music through the period of Japanese Occupation should not be regarded as just one of the musical characteristics of the period or reenacted in an optimistic manner. When considering the court ceremonies during the period of Japanese Occupation, the context of what happened to Yiwangjik aakbu should first understand; this will allow us to determine which parts of the ceremonies are to be carried on and which parts are to be objectively described.