This study aimed to explore how the peer support programme gave influences on technical high school pupils in Japan. The study invited a total 76 pupils (37 in an intervention group and 39 in a control group) to be involved into the peer support programme and assessments. The participants were annually assessed three times by adopting four scales, which examined their interpersonal relationship level, self-esteem, mental health, and school environmental adaptation states. The results showed that pupils in the intervention group (the peer supporters) tended to improve their own skills and abilities in terms of all the scales after joining the programme. Also, in terms of Adaptation Scale for School Environments on Six Spheres (ASSESS), which was a newly developed scale, there were no significant positive influences in both areas of "fulfillments in study" and "peer support activities against bullying". As a conclusion, even in the technical high school where the majority of pupils were male, the peer support programme gave positive influences on the intervention group (the peer supporters) in terms of interpersonal relationship level, self-esteem, mental health, and school environmental adaptation states. [Note: The publication year (2023) shown on the PDF is incorrect. The correct year of publication is 2024.]