Abstract: Ningen Shikkaku is one of the representative masterpieces of Osamu Dazai, who is a world renowned Japanese writer.It narrates the life experience of the main character named ōba Yōzō’s in three different phases childhood,adolescence and adulthood.With an exquisite psychological description,the picture of how he gradually lost his qualification as a human being and finally ended up in self destruction was drawn.Based on some theoretical studies on mutual trust in psychology and an in depth analysis on the relations between three different groups of people(i.e.:the relations between ōba Yōzō and his father,his companion Masao Horiki and his wife Yoshiko respectively),this paper intends to disclose the fact that ōba Yōzō’s “fear towards other human beings” originates, in nature,from his distrust towards interpersonal relations.This paper also aims to raise the readers’awareness on the realistic meaning of how we should live as human beings.

Key words: Ningen Shikkaku, Osamu Dazai, literary psychology, sense of distrust