komen the role of lesson study The study analyzes the impact of “Lesson Study”-based school experience program on the improvement of preservice teachers’ teaching competencies. Unlike the usual school experience program, the “Lesson Study”-based school experience program required the preservice teachers to follow steps of “Lesson Study”, i.e. plan, do, and see. For the purpose of the study, lessons taught by the preservice teachers’ are fully documented using a video camera. In addition, a students’ questionnaire was also administrated to collect data on classroom emotional climate. Analysis of the videos find that the pre-service teachers’ can perform most indicators of teachers teaching competencies. The utilization of teaching resources, however, is still limited. Analyzes of the questionnare show that classroom emotional climate is quite good. The findings suggest that the preservice teachers’ participated in “Lesson Study”-based school experience still shown some weaknesses in their teaching. During the reflection sessions, however, the pre-service teachers admitted that “Lesson Study” based school experience program provided them with meaningful insights on how to improve their teaching competencies