Opera is the most comprehensive musical art. In recent years, contemporary opera worlds has seen a variety of attempts to reinterpret operas of the past in a modern light. This has resulted in a dramatic change in the production of musical style and stage art. The purpose of the study was to modernize and streamline opera costumes by extending the scope of existing stage costume design, through the reinterpretation and application of the decorative elements in the Middle Age of Rococo, such as ruffles, frills, shirring, embroidery, buttons, etc., in such a way as to effectively communicate the moods of an opera to a modern audience. The costumes of the Rococo period were reinterpreted in a modern way, with the following results. First, in this work, the male main character was played by a bass to express the image of an older, lazy, rich man. A key element in modernizing the stage costume was selection of the costume color in such a way as to visually represent the voice tones sung by the major characters in the opera. Second, the maid hat and aprons were decorated with frills by applying the curves of Rocaille decoration from the Rococo period symbolize the role of the maids. This represented the distinction between occupation according to class and status at that time, while also expressing the ideals of modern feminine beauty. This makes for more comfortably-worn costumes, and is economical for production expenses. In the future, the stage costume design for classical opera will need to be revised consideration of a modern viewpoint.