Section leader is the leader of each voice section. The section leader has extra tasks compared to regular singers, so higher self-efficacy is required. This study aims to explore the dimensions and sources of efficacy that influence the formation of self-efficacy in the section leader of the Student Choir Group (Unit Kegiatan Mahasiswa or UKM) Paduan Suara. This study uses a qualitative approach with a case study method. Data were obtained from semi-structured interviews and analyzed using thematic analysis techniques. The research participants were two section leaders with a minimum tenure of one year. Referring to the dimensions of self-efficacy developed by Bandura, both participants were able to maintain self-efficacy supported by sources of efficacy including (1) personal experiences of achieving success, (2) the success experiences of others as role models, (3) emotions arising as responses to the situations faced, (4) and verbal persuasion from people around them. The sources of self-efficacy obtained by the section leaders were able to motivate the participants and make them confident in carrying out their tasks effectively.