Teachers play an important role in school guidance and counselling in Asia, but in Japan, there is an issue with teacher training for their counselling skills. This study examines what kind of competence-building affects the development of school counselling skills of preservice teachers by receiving supervision using AI analysis of role-play recordings. Both the supervisors and the supervisees role-played and recorded their sessions. Then, the supervisor supervises the preservice teachers based on objective indicators using AI analysis. After that, the authors analysed feedback comments from preservice teachers and supervisees on those supervision sessions. As a result, being supervised using AI analysis of role-play recordings and reflecting specifically on what they said and did in their counselling situations were shown to lead to deeper reflection in preservice teachers. The results of this study show that supervision using AI analysis has an effective function as a practical competence builder for teacher education in the future.