Recently, many researchers and scholars have focused on reflective teaching to support good practices in teaching. For effective reflection, it is necessary to encourage teachers' reflection by promoting collaboration during which they can discuss various teaching issues and problems while supporting each other. The purpose of this study was to investigate Korean preservice music teachers' experience in collaborative reflection sessions. I used data collected through observations, the participants' reflective journals, and individual interviews. The results showed that as the participants gained experience while observing and teaching music classes, the contents of their reflections on technical and practical matters became more varied. Additionally, the participants' reflective thinking, applied critically, tended to focus on the social context of the music classroom. In addition, participants predominantly showed technical level of reflective thinking rather than practical and critical levels. Finally, the results revealed that the collaborative approach enabled prospective music teachers to broaden the scope of their reflective thinking, and a sense of emotional safety in the collaborative group allowed them to honestly confront their own teaching worries and problems.