When depression develops during adolescence, it hinders thinking from developing. Even when thinking is developed, a positive outcome can’t be brought because the individual tends to think negatively. When they want to do something, they can’t act as they intend to. Therefore, they lose confidence. They become too sensitive in interpersonal relationships and feel uncomfortable going out in a crowd. Then, they lose confidence in their interpersonal relationships. Sometimes they become more dependent ("amae"). They start to present regressive behaviour and consequently their self-esteem is lowered. This leads to a crisis in identity formation. In order to cope with this problem, they need to understand the nature of depression. There are several points to this. Firstly, because depression is an illness, they need to keep a distance from themselves. That is, they need to objectify the depression. They should think of it as nothing to do with their own personality. This is quite difficult to do, though. The less they have self-affinity, the better they become. It is estimated that the prevalence of depression is 6‐8% in adolescents. Hence isn’t it required that such a high-frequency disease should be taught in educational institutions from the perspectives of self-esteem and suicide prevention?