The "Annals of the Joseon Dynasty (朝鮮王朝實錄)" is the precious historical material which contains royal culture of Joseon dynasty as an official document. It kept a record of the diseases and treatments relating to the 27 Kings for a period of 518 years, who had a variety of different symptoms. Among them the most frequent disease was a skin disorder such as a boil of a painful infected swelling. Dermatosis became the direct cause of death of several Kings. In this article we tried to conduct research using the "Annals of the Joseon Dynasty" into the skin diseases of the Kings during the first period of Joseon dynasty from the first King Taejo (太祖) to the 12th King Injong (仁宗). Among the 12 Kings, the 5th King Munjong (文宗), the 7th King Sejo (世祖), the 9th King Seongjong(成宗), the 10th King Yeonsangun (燕山君), and the 11th King Jungjong suffered from dermatosis. The King Munjong died at the age of 38 and suffered from severe boils before his death. The cause of death is thought to be septicaemia. The King Sejo does not have any specific record of skin disease, however, the recently discovered relics showed the indications of serious skin trouble of boils. The King Seongjong suffered from skin diseases at the age of 20, 27, 28 and 38. Nevertheless, the direct cause of death was not dermatosis. The King Yeonsangun had skin trouble of boils on his face when he was 20. He lost the throne and died of an infectious disease at 31. The King Jungjong had a record of suffering from dermatosis at the beginning of twenties, at the middle of forties, and at the age of 57 when he died. The skin trouble affected the whole of the body. He was treated with acupuncture therapy and medication for both internal and external uses among which folk remedies were included.