PURPOSE: To exactly bury a pile in support layer by a method in which a tip- expandible shoe by which ground bearing force more than the compressive strength of a pile is held is attached to the tip of a casing at a time when the casing is normally turned or separated from the tip at a time when the casing is turned reversely.

CONSTITUTION: An injection tube D is inserted into a casing C, and a boring liquid is supplied from the injection tube D and injected from the tip of a tip expandible shoe B, durng which excavation is continued while normally turning the casing C. When the shoe B reaches a given depth, the turning of the casing C is stopped and then the injection of the boring liquid is stopped. Then, a ready-made pile A is inserted into the casing C and set on the shoe B, cement mortar is charged through the injection tube D to harden the root of the pile A, the casing C is reversely turned, and the casing is gradually pulled out while pushing soil and sand into the surrounding area of the pile by the blade 15 of the casing.