The purposes of this study were to find factors to influence on experienced teachers` professional development. All three biology teachers participating in this research have got master`s degree in science education, and have used instructional model for enhancing students` understanding of abstract concepts in biology. Data were collected through the interviews which include the teachers` narratives on their professional development on teaching. The results indicate that the professional development of the three teachers involved followed three stages in common: to teach as they have experienced, to get various repertoires on teaching, and to reorganize their own instruction. The three teachers thought the intrinsic elements based on their reflections were key factors in their professional development. It is suggested that an environment and systems to support teachers` professional development should be provided for teachers to get chances to observe their own class and reflect on their teaching.