To provide piping structure of enhanced workability for an underground heat exchange well capable of restraining dispersion of heat exchange performance in the plurality of underground heat exchange wells and capable of reducing conveying power for a heat exchange body.

A plurality of heat exchange pipes 76A-78A with the heat exchange body flowing therethrough is connected respectively in series to a plurality of heat exchange pipes 76B-78B to form two lines of flow passages 73, 74, the heat exchange pipes constituting respectively the flow passages are inserted respectively into a plurality of hollow piles 70, 71, 72 buried into the underground 6 under a building 2 to form the exchange wells 7, 8, 9, and end parts of the flow passages are connected respectively to a piping part 10 connected to a heat pump 4, so as to make directions of the heat exchange body flowing through the flow passages directed reversely each other.