PURPOSE: To firmly fix an inner cylindrical body by a method wherein the inner cylindrical body is fixed by screwing to the inside of an outer cylindrical body so that the height thereof can be adjusted freely, and an anchor member detachably provided to the inner cylindrical body is made to project into the inside of pavement.

CONSTITUTION: An anchor member 17 is screwed from the upper inside of an inner cylindrical body 4 and is fixed so that the front end thereof can be projected to the outside. The inner cylindrical body 4 is turned round inside an outer cylindrical body 1 and is made to move up and down for adjustment so that the upper end of the inner cylindrical body 4 can be flushed with the ground surface. Then, the inner cylindrical body 4 is turned round so that a pressing device 15 can be coordinated with a nearest one of a plurality of recessed parts 8 provided to the outer cylindrical body 1. The leg part of the pressing device 15 is brought into contact with the inner circumferential face of the recessed part 8 through a notched hole provided to the inner cylindrical body 4, and is fixed firm with a fixing bolt 16. The cylindrical bodies are buried underground or into the inside of pavement made of asphalt or the like, and turning and rocking of the inner cylindrical body 4 are prevented certainly with the anchor member 17. Thereby, the inner cylindrical body 4 can be fixed effectively for a long period of time while readjustment of height can be made without removing earth and sand on the surroundings as the anchor member is detachable.