This study investigates the level of teacher self-efficacy (TSE) among 90 secondary preservice teachers (PSTs) before their first teaching practice and the factors which influenced their ratings. The Scale for Teacher Self-Efficacy (STSE) (Pfitzner-Eden, Thiel, & Horsley, 2014) was adapted by adding some open-ended questions. Data were analysed via SPSS and NVivo separately. Results show a relatively lower level of TSE compared with previous research and classroom management was of greatest concern. PSTs reported factors such as lacking teaching experience, previous informal teaching and other relevant experience, teacher education program, personal qualities and characteristics, and teacher-student relationship. Implications, limitations, and suggestions from the study are discussed.