This study examined the factors affecting the self-efficacy in music student-teachers throughout their student teaching experience as a means to improve the strategic plan of the music student teaching experience. Bandura's self-efficacy theory and its dimensions provided the theoretical framework. The data sources included a series of interviews of seven music student-teachers and the researcher's observations of the student teaching seminar classes. This study found that four physiological factors affected the self-efficacy levels of student-teachers: Readiness from Curriculum, Surrounding Challenges, Stress Coping and Hindering Mechanisms, and Constructive Criticism. Discussion included a connection to Bandura's self-efficacy theory as well as implications for practitioners and researchers.