A pipe well; a ground water outlet pipe inserted into the pipe well; a submerged pump installed at the ground water outlet pipe; a heat exchanger in which the ground water is circulated and terrestrial heat of the ground water is heat-exchanged; a collection pipe collects the ground water circulated through the heat exchanger into the pipe well; a connection pipe which connects the submerged pump and the heat exchanger; an auto temperature bypass apparatus which is installed at the connection pipe to automatically bypass the ground water from the connection pipe when a temperature of the ground water arrives at a predetermined value; a discharge pipe through which the ground water bypassed is discharged; and a ground water restoration hole adjacent to the pipe well in which the discharge pipe is inserted to fill up the ground water nearby.