This study explored the impact of the peer support programme on pupils at Japanese technical high school for over 6 years. A total of 268 pupils (an intervention group 112; a control group 114) were invited for the study and the pupils of the intervention group were given peer support training and they joined its supporting activities. All the pupils were assessed three times by adopting IRS, RSES10 and GHQ28. The results showed that the programme seemed to give positive influences on the peer supporters in terms of IRS, RSES10 and GHQ28. Also, both group members were classified into low-scoring groups and high-scoring groups, depending on their scores at the first assessment. Then, the results of analysis showed that the pupils from both low & high-scoring groups significantly improved their scores in IRS. In RSES10 and GHQ28, the pupils from the low-scoring groups improved their scores, but those from the high-scoring groups did not improve much. As a conclusion, even in a technical high school where the majority of pupils was male pupils (over 90%), the peer support programme seemed to give positive influences on the peer supporters in terms of IRS, RSES10 and GHQ28.