This study is aimed at these research gaps in the regulatory focus theory, develops and tests a research model in Taiwan's National police Administration setting, which investigates the relationship among transformational leadership, regulatory focus and organizational commitment. The subjects of this study are 500 full-time employees in National Police Administration of Taiwan. Structural Equation Modeling was used to test this study model. These results are that transformational leadership has a positively significant influence on promotion focus and affective commitment. The role of promotion focus plays a mediator in the relationship transformational leadership between and affective commitment. In addition, promotion focus has positively significant influence on affective commitment. Implications, limitations and directions of future research are discussed.