In this paper, I consider the role of Zunichi's diary and an actress Oyuki, and a characteristic of Zunichi's image, in the process of decision that Koizumi Zunichi who is hero in Ougai's SEINEN(SUBARU 1910.3~1911.8) intend to write a novel based on Japan's traditional world, give up to write that based on present ages. Zunichi has images of youth that new from the country. And he also has images of middle age. That is a similar to the Meizi's image but a appropriate image to draw the image of youth that desire to go back a traditional world for getting disillusioned at present ages. And that is the sense in which Ougai doesn't give up to write a novel based on present society. And an actress Oyuki who has a modern image play a role in sparking Zunichi's sexual desire. A woman who light his sexual desire is a actress Sakai. She is a character with a symbol that he intend to draw the present ages. This relation with an actress sakai present as a form of confession diary. Finally he decide that he leave an actress sakai for disillusionment about the relation of an actress sakai without a love. At a time he decide that he write a novel based on not Japan's present ages but traditional world.