Leadership is very important for the process of school improvement and implementation in the context of education (Colton, 2016). The purpose of this research was to determine the impact of principal transformational leadership that has been practiced in four main dimensions on the teacher's self-efficacy. Four dimensions of transformational leadership will be emphasized in this research such as idealized influence, individualistic consideration, intellectual stimulation, and inspirational motivation. The research problem of this research is how leadership practices practiced by leaders can improve the effectiveness of teachers in teaching needs to be addressed (Siti Noor Ismail et al., 2018). This issue has been supported by Dronnen-Schmidt (2014) about whether some strength in leader characteristics can predict a leader's transformational leadership style related to self-efficacy. Teachers with high self-efficacy should be studied to determine if having the possibility of spirituality is an important factor in why teachers believe that they are effective (Barsh, 2017). Therefore, this research is important to conduct because it focuses on the preschool context.

Keywords: Transformational Leadership, Private Preschool, Self-efficacy, Principal