The present invention enables easy construction of a foundation pile having a rigid structure even at a site where a pile produced in a factory cannot be brought in. The tube 1 having a forming material filling port 1a at a top end and a closed bottom 1b at a bottom end is set in a suspended state, and foundation pile forming material 4 is filled from the forming material filling port 1a into the tube 1 in the suspended state. A composite foundation pile 5 in which the tube 1 and the filled forming material 4 are integrated is formed, and the composite foundation pile 5 is driven into the ground 13 or inserted into a borehole 12 formed on the ground 13.