This paper represents the reality and historical position of Houshi-Onmyoji. Onmyoji or Onyoji is the member of Onmyodo or Onyodo, which was the expert group of divination and magic in the ancient and medieval Japanese court and government. The government prohibited monks to use divination and non-Buddhist magic with their status in A.D.701. However, a Houshi-Onmyoji in the Heian period was a monk and a Onmyoji at the same time. It was believed that they used divination and magic different from what the official Onmyoji, so-called Kanjin-Onmyoji did. However, Houshi-Onmyoji, in the historic documents and literary works of the Heian period, used the divination “Shikisen” and magics, for example, “Harai”, “Shuso” and so on, which the official Onmyoji also used. The official Onmyoji and Houshi-Onmyoji has the same origin. The origin is the syncretic Buddhism in the ancient Chinese and the Korean peninsula. After prohibition of dual work of monk and Onmyoji in the Japanese court, the monks could not become the official Onmyoji. But many lower-class monks used the divination and non-Buddhism magic. In the latter 8th century, Onmyodo was established, when the codes of Onmyodo were also determined. Some magicians of lowerclass monks shared the codes of Onmyodo, then they were called “Onmyoji” or “Houshi-Onmyoji”. In the Heian period, aristocrats believed that gods and goddesses were afraid of Buddha and Buddhist monks. As a result, Houshi-Onmyoji monks hid their skin heads and did magic for gods and goddesses. It is assumed that they did dual work for living expenses. Therefore, they were considered to be immoral. In Kamakura period, that idea that the gods and the goddesses feared Buddhism went out of fashion. Thereby, Houshi-Onmyoji disappeared.