To provide a rotary buried post capable of holding sufficient horizontal bearing power while improving penetration speed without causing noise and head deformation with extremely simple structure.

This post is formed with valley parts 3 obliquely recessed toward the center from three directions on the tip side outer periphery in the open state of the tip part of a steel pipe 2, and blades 5 formed continuously with the valley parts 3 between the adjacent valley parts 3. The post is buried underground 10 by taking in soil 6 on the steel pipe inner side from a tip opening part 4 and discharging soil in the valley parts 3 to the outside at the same time while scraping the soil 6 by the tips of the blades 5 by the rotation of the blades 5.