Construction method for foundation pile

The purpose of the present invention is to enable easy construction of a rigid structure foundation pile even at sites to which piles produced in factories cannot be brought. A tube (1) having a forming material filling opening (1a) at the top end and a closed bottom (1b) at the bottom end is in a suspended state, and while in a suspended state, a forming material (4) for the foundation pile is poured into the tube (1) from the forming material filling opening (1a) and a composite foundation pile (5) is formed in which the tube (1) and the forming material (4) that is poured are unified, and the composite foundation pile (5) is either driven into the ground (13) or inserted upright into a borehole (12) formed in the ground (13).