The purpose of this study is to articulate the pedagogical content knowledge of music classes of pre-service teachers in the elementary level, observing specific music lessons. 112 participants were currently enrolled in G university of Education and they were mostly sophomores. All these participants were required to observe specific music lessons and wrote class critiques. The collected data from this study were analyzed with Grounded Theory which included categorizing the data with the specific themes by using opening coding. The coded data were analyzed by frequencies in Descriptive Statistics. The result revealed that when pre-service teachers observed and analyzed music classes, they paid more attention to the general pedagogical point of view rather than the musical contents knowledge. These participants tended to dissecting all components of music education into a general pedagogy, music, teacher, and student while they were observing and analyzing music lessons. These fragmented pedagogical knowledge and their past experience of music lessons led them to developing misconceptions and prejudice. At the same time, this study was also shown that pre-service teachers had attempts to doing self-reflection of the music lesson through modeling a teacher who taught the music lesson that they observed. A researcher was able to discuss the implications of the emerging music curriculum and to suggest the importance of the pedagogical content knowledge of music classes which was enhance music teachers` capabilities for teaching by observing good music lessons and which expanding and settling Subject Dedicated System in Music Education.