Abstract-The objectives of this study was to investigated in-depth understanding of teachers' efficacy by identifying the structural relationship of factors that influence teachers' efficacy in terms of principal's leadership, organizational commitment, social support, and psychological capital. A quantitative research design was conducted within purposive sampling method were used for data gathered from 204 high school teachers in Taiwan. The validated paper-pencil based questionnaires were employed in the study and analyzed undertaking descriptive analysis, confirmatory factor analysis (CFA), and structural equation modeling (SEM). Findings revealed that both principals' leadership and social support played a crucial role as a mediating factor that highly contributed to organizational commitment in enhancing teachers' efficacy. Finally, some suggestions were proposed for future research bridging theoretical and practical understandings of the formation and improvement of teachers' efficacy.