To easily maintain the quality of a bearing pile to be installed in the same position, while reducing labor for drilling a deep well hole.

A pile hole 5 is drilled; the deep-well hole 1 with a diameter smaller than that of the pile hole 5 is drilled in a hole bottom through the pile hole 5; a column pipe 3, the lower end of which is connected to the pumping pump 2, is inserted into the deep-well hole 1, so as to form a deep well W; and a bearing pile forming material K is positioned in the pile hole 5, so as to form the bearing pile P with a diameter larger than that of the deep-well hole 1.