Sokutai (束帯) was a compulsory dress code for the attendance of any ceremony or meeting conducted by the government. It was developed after the 10th century, along with several other national customs. Although sokutai was a normal dress code for nobles during the Heian Period (794‒1185) in Japan, nobles dressed differently according to their rank and the place of the event. Therefore, there were many different types of clothing designated for nobles to wear in various situations. The main types of the clothes they wear consist of sokutai, noushi (直衣), houko (布袴) and ikan (衣冠). This article discusses the ways that nobles dressed accordingly to their rank the attire designated in the place of event or workplace, and the ways they changed their clothes when they realized they were wearing unsuitable clothing compared with others at the Imperial Palace. An examination of ancient history in Japan verified that nobles wore different types of attire based on the function of their work.