The purpose of this study is to investigate the school administrator’s strategies for persuading teachers as well as the factors for teachers to participate in the free semester system. It is based on the case study of the free semester system research school. As a result, both the school administrator and teacher candidates for promotion played a significant role in accepting the free semester system. For persuading teachers, the following strategies were used: ‘Do not wear clothes made by others,’ ‘Create productive conflicts among teachers,’ ‘Interview one-on-one.’ The factors for teachers, the key part for operating the free semester system, could be categorized into individual, relational, cultural, and organizational factors. Individual factors included ‘teacher’s professional development’ and ‘student’s change and satisfaction,‘ while relational factors had ’trust between administrators and teachers’ and ‘bond among teachers.’ ‘Educational morale and accountability’ and ‘things we should do’ were analyzed as cultural factors. At last, organizational factors included ‘school administrator’s leadership,‘ ’guidance by department’s head teachers,‘ ’fair workload,‘ and ’extrinsic rewards.‘ Based on results, this study suggests the necessity for following factors: in-service training for school administrators, operating principles for effective task force team, supports for encouraging the intrinsic factors.