The purpose of this study is to investigate the causes of clothes phenomenon of the ruling class women on the Heian period of Japan in the aspects of politics, economics, society, culture, and religion. The findings of the study are as follows. The main characteristics of the Heian period of Japan may include a rare sense of internationalism, low sense of nationalism, and frequent cases of political intrigue. However, noble culture, centered on royal court, was flourished and it enabled to develop sophisticated and graceful culture. During the Nara period and the Heian period (from $8^{th}$ to $12^{th}$ century), there were enormous changes in the clothes, starting from the mid $10^{th}$ century. The clothes of the ruling class in the Heian period underwent changes from the imitative clothes-imitating the clothes of the Tang age of China- to Japanesque clothes-adding the aesthetic consciousness of Japanese ruling class people. Particularly, the clothes of the ruling class women became massive, majestic, and decorative. The changed clothes had also features such as layered look, utilizing underwear as outer garments, using a wide variety of colors, and using hard and solid materials to make clothes. It can be concluded that the clothes of the ruling class people in the Heian period were affected by plural factors such as national and international political situation, economics, society, culture, and religion. The clothes were used by ruling class people as means of expressing their noble and sophisticated beauty, which led to produce humanistic beauty. The Heian period can be described as an era of the highest reach of humanity.