To provide a method for installing a reinforcing bar cage for cast-in-place pile and a ground heat use heat exchange pipe for improving heat exchange efficiency by installing a heat exchange pipe near a pile hole wall without damaging it.

Disclosed is a method for building a reinforcing bar cage 1 in a pile hole 2 and then installing a heat exchange pipe 5 for ground heat use in the pile body of a cast-in-place pile constructed by installing concrete, in which the heat exchange pipe 5 extending to an axial direction is mounted so as to freely oscillate along a vertical plane on the outer periphery of the reinforcing bar cage 1, and the reinforcing bar cage 1 is built in the pile hole 2, and the heat exchange pipe 5 is then moved to the pile hole wall side with a flow pressure due to the installation of concrete.