This study aimed to develop a scale of the nine key competencies for students of G National University of Education (GNUE) as a pre-service elementary school teacher and to examine its validities. The detailed steps of the research process are following. First, based on a previous empirical study of GNUE, the study developed 174 candidate items and assessed the content validity of the candidate items by 15 experts in the field. Second, as a preliminary test(total of 145 items), responses of 424 students of GNUE were statistically analyzed to evaluate the items and the sub-scales’ quality. Third, the preliminary data analysis resulted in 79 items, administered to 390 students of GNUE again. Statistical analysis of the items and scale’s quality through reliability analysis, confirmatory factor analysis showed construct validity and convergent validity. As a result, the study revealed the final 69 items for nine key competencies and identified two big domains of competences as a general competence domain (six competencies) and a specific competence domain(three competence). Additionally, using another students’ sample of GNUE(N=214), the scale’s measurement invariance was confirmed. Finally, the implications of the findings were discussed, and suggestions for further studies were provided.