From the viewpoint of historical institutionalism, this paper explored the internal and external factors influencing policy changes of teacher evaluation for professional development, TEPD, and the question as to how TEPD policies were implemented to trigger teachers’ professional development. By looking into how TEPD policies were formed structurally at each phase and what factors impacted the policy during its implementation, this study presents the changing paths of the TEPD’s implementation as a whole. The results indicate that changes in policy implemtation took place at two vital phases induced by the factors of the internal re-organization of the Ministry of Education and the transformation of TEPD. There are also climacteric, unpredictable non-structural factors during this period of time that inflate our understanding of teacher professional development. In short, the main findings are as follows. (1) With a huge gap between their understandings of TEPD, different interest groups tried various ways to influence policy implementation. (2) In spite of the periods of ups and downs, the policy has been implemented over the past ten years without major changes or revisions. The policy has created a paradigm and systematic shift for teacher professional development, because it highlights crucial ideologies such as “continuous growth as a teacher” and “teacher as a profession.” (3) The newly transformed teaching methodologies can be conducted concurrently with TEPD practices. However, it appears in each county/city that different teachers and different staff members in charge of the plan are not equally acquainted with the plan and that their comprehension of the plan varies significantly. In the future, a polarized predicament in terms of being familiar/unfamiliar and enthusiastic/perfunctory might arise, as could the problem of merely pretending to do the work yet not making any substantial progress.