Executing a successful teaching practicum is closely related to effective collaboration between preservice and cooperating teachers. Thus, this study implemented and investigated collaborative inquiry between preservice and cooperating music teachers in Korea. The results showed that the preservice music teachers played an important role in theoretical application based on their recently acquired knowledge, whereas the cooperating music teachers challenged their thinking by offering practical perspectives grounded in their experiences. The different roles enabled the connection of theory to practice in music education and the active participation from both groups. In addition, sufficient time for the preparation of instructional strategies and shared visions positively affected the equally important roles between the preservice and cooperating music teachers, whereas lack of time and opportunities to reflect on teaching practices after lesson implementation hindered collaborative inquiry. These findings support the previous literature, which suggests that collaborative inquiry could be an effective tool for teacher collaboration, by applying collaborative inquiry to the specific context of collaboration between preservice and collaborating music teachers.