In recent years, the use of educational data has been promoted in schools. The merits and demerits of Evidence Based Practice, which aims to link evidence derived from educational data to improvements in practice, have been discussed. However, practical suggestions are lacking in school settings, where various factors are intertwined. Therefore, in this study, a school where ‘EBP Thinking’ was developed was surveyed, and a case study was conducted to elucidate what triggered the change, what happened and how the school organisation and individual teachers were transformed. As a result of interviews with several staff members, a series of transformations such as ‘exploration and passive triggers → shared EBP thinking → team formation → practice（educational data meetings and classroom practice）, EBP mentors → reflection → consolidation of EBP thinking’ were identified. Through this study, the significance of reflection on EBP thinking, the existence of EBP mentors and the fostering of EBP thinking was suggested.