The purpose of this study is to explore the relationship among principal's moral leadership, teacher's motivational self-concept, and teacher's commitment to teaching. The correlations of these three variables and the effects of principal's moral leadership and teacher's motivational self-concept on teacher's commitment to teaching were also analyzed. The study verified the hypothetical path model, and examined the direct and indirect effects of principal's moral leadership on teacher's commitment to teaching. The results of the study show that there are significant positive correlations between principal's moral leadership, teacher's motivational self-concept, and teacher's commitment to teaching. It was found that principal's moral leadership affects teacher's motivational self-concept and commitment to teaching, and that teacher's motivational self-concept serves as a positive mediator to the effects of principal's moral leadership on teacher's commitment to teaching. Thus, the principal, as a leader of school organization, should recognize the importance of teacher's motivation and should encourage teacher's motivational self-concept to enhance teacher's commitment to teaching by managing school organization effectively.