To provide an underground heat exchange system which enables efficient heat exchange by excavating a region surrounded with an underground continuous wall to form an excavation space securing water stop performance and laying a heat exchange pipe in the excavation space.

The underground heat exchange system includes: the underground continuous wall 11 reaching an impermeable layer 7; the heat exchange pipe 20 laid on the excavation bottom 13 in the excavation space formed by excavating the region surrounded by the underground continuous wall 11; and a supply pipe 18 supplying the underground water of a confined aquifer 8 deeper than the impermeable layer 7 to the portion where the heat exchange pipe 20 is laid.