This study will focus on analyzing the notes of the tenor aria and vocal ensemble in the work of Verdi’s Opera Seria,〈Un Ballo in Maschera〉and 〈Otello〉, which are representative of 19th century Italian opera. Before reviewing the tragic love of tenors in opera, Verdi's life and the tendency of works that changed depending on period will be examined through the characteristics of opera in the 19th century. In this study, the composition background of each opera, plot, outline and content of the work will be examined. An additional purpose is to examine how the play progresses through lyrics, the structure and form of the song, melody, chords, accompaniment, and orchestral techniques in the tenor arias “Ma se mè forza perderti” and “Ora e per sempre addio” as well as the vocal ensembles “Teco io sto” and “Dio ti giocondi, sposo” based on the changes in compositional tendencies of the mid and late operas of Verdi. In addition, it will review how it was led by the tenor as well as the singing techniques were on display. Also, it will help in understanding the use of the leading motif through note analysis and how to express internal emotions in the songs until the tragic death of the duo through duet. The hope is that this can be used as basic data to be referred to by performers and the audience by analyzing the musical changes of Verdi to express the script.