To provide an environment control system hardly affected by the magnitude of inclination of slope.

This water circulation type environment control system comprises a conducting tube having its basic end at a first altitude, its folded part at a second altitude lower than the first altitude, and its tip adjacent to the basic end, and a water feeder for feeding the water from the tip to the basic end of the conducting tube, the basic end of the conducting tube is placed at a position higher than the tip, the water is circulated along the conducting tube by feeding the water to the basic end by the water feeder, a cold storage portion is disposed at a prescribed position in a low temperature region having a temperature lower than the air temperature to cool the water, and a cooling portion is disposed in an internal space of a structure at a downstream side of the cold storage portion to cool the internal space.