To reduce cost by pulling out a leading steel pipe of an underground heat exchanger while reversely rotating it when installing the underground heat utilizing heat exchanger in the ground.

An underground heat exchanging method comprises mounting a blade plate 6 of spiral structure to the outside of the tip of the leading steel pipe, installing the leading steel pipe 5 opened at the bottom part, while rotating it, removing sediment in the pipe, arranging the underground heat exchanger 1 in the pipe, then pulling out of leading steel pipe while rotating it reversely, and back-filling gravelly soil, sandy soil and field soil into a void in the hole after removing the steel pipe.