The Heian Age in Japan was the period of about four centuries which was under the aristocratic rule represented by the Fujiwara family. During the age with kana characters invented, the people came to express their thought and feeling better and more freely. From 10th to 11th century a dynasty culture sprang into blossom centered around the court and nobility. This age also saw the publishing of Chokusenwakashu (a waka anthology compiled by the royal order) and the creation of a variety of romantic literature by the court ladies. While keeping the tradition socially and politically, the men were wasting their energy on the study of Chinese characters, the women released their literary talent through kana characters, bringing about eventually the revolutionary change of the use of letters. Conventionally the diary had been kept in Chinese characters of the official ceremonies and practices ; now it came to be kept in Japanese characters, which trend created the diary literature, with the appearance of Tosa nicki followed by Kagerow nicki, Izumishikibu nicki, Murasakishikibu nicki, Sarashina nicki and Sanukinosuke nicki. The result of the study of these diaries and their writers to seek out the character of them and the consideration of their influence on the literature of later days is as follows. The character and Influence of the Diary Literature of the Heian Age I Character 1. Tosa nicki is a travel diary, while the others are the records of daily life written by ladies of the court and aristocratic class. 2. In the age when Chinese characters were held in reverence, the diary writers developed kana characters. 3. Though Kino Tsurayuki, the writer of Tosa nicki, for the first time wrote the diary assuming a lady, all the other writers were ladies. 4. Ki was a descendant of the nobility and all the other writers came from the Fujiwara family. 5. As the writers were all poets of the Heian Age, many wakas are found in the diaries. II Influence 1. Establishment of kana literature (Tosa nicki). 2. Pioneers of female diary literature (Kagerow nicki). 3. Introduction of realistic literature leading to Genjimonogatari (Kagerow nicki). 4. Materials for the study of thought and feeling of the author of Genjimonogatari (Murasakishikibu nicki). 5. Leaving rich poetic feeling in waka. 6. Handing down romanticism and developing the idealistic spirit of Murasakishikibu (Sarashina nicki). 7. Important historical materials : records of disease and death, religion, various officials in the court, the court life, etc.