The purpose of this study was to develop a job competency model for primary school master teachers. Through literature review, behavioral event interviews and in-depth interviews, a draft job competency model was developed, and focus group interviews were conducted to develop a tentative job competency model. Then, a content validity study was conducted with 20 experts to obtain CVI and IRA values, and the final job competency model with validated job competencies and behavioral indicators was confirmed. The job competency model of elementary school master teachers consists of four job areas (supporting school education, student education activities, supporting teacher professional development, and research and development activities), nine job competencies (supporting school educational goals, responding to changes in the educational environment, curriculum literacy, learner orientation, teaching expertise, instructional consulting, teacher professional coaching, learning organization, and master teacher professional development), and 33 behavioral indicators. It is significant that the model of master teachers' job competencies developed in this study provided a systematic understanding of master teachers' job competencies.