This study aimed to investigate the self-efficacy of EFL pre-service teachers and the challenges they experienced during microteaching classes at the English Department of Mulawarman University. This study used a single case study research design with a qualitative approach. The participants in this study were six EFL pre-service teachers for the 2019/2020 academic year who were selected based on predetermined criteria. The researcher used a reflective journal and interview protocol to collect the data and analyzed it using thematic analysis adopted from Braun and Clarke (2006). The researcher found that the participants in this study had good self-efficacy in all three categories of self-efficacy constructed by Tschannen-Moran and Hoy (2001) including: student engagement, classroom management, and instructional strategy categories. The pre-service teachers also experienced several challenges, such as; 1) designing a lesson plan and teaching media, 2) managing students, time, and voice, and 3) controlling feelings and thoughts during teaching practice in microteaching classes.