Thai education reform set the transformation from teacher-centered teaching into learner-centered approach as a pillar. As a part of reform Regulation of Public Teachers and Educational Personnel Act and Teachers and Educational Personnel's Salary and Allowance of Position and Career Act were promulgated all at once in 2004 and the teachers' personnel administration body was reorganized, teachers' responsibilities became welldefined, and remuneration of teachers had greatly improved. This study examines the significance of teachers' personnel administration reform by comparing it with the previous one in above-mentioned three aspects. Consequently, the structure of personnel administration bodies shows the integration of primary and secondary teachers' personnel administration where the quality of administration bodies becomes more professionalized. Teachers' diverse responsibilities had slimmed in horizontal range given the shift from a living moral example and relationship with colleagues as well as with the community aside from teaching into more specialized in teaching and it becomes sophisticated in a deeper level. Teachers' remuneration and career path was modified very high range with a long scope which will be a strong incentive. In short, the significance of the reform has transformed the system of teachers' personnel administration into an enhancement of the teachers' professional development.