A water evaporation type cooling system equipped with a hermetically sealed housing and a solid electrolytic membrane placed to divide the hermetically sealed housing into first and second hermetically sealed spaces. Water is reservoired within the first hermetically sealed space, while a condenser is situated to communicate with the second hermetically sealed space. A direct-current voltage is applied to the solid electrolytic membrane, with the result that a water electrolytic reaction takes place on its first hermetically sealed space side surface, while a water production reaction occurs on its second hermetically sealed space side surface. Protons produced by the water electrolysis pass through the solid electrolytic membrane to contribute to a water production reaction. Steam within the first hermetically sealed space is transferred to the second hermetically sealed space whereas the oxygen within the second hermetically sealed space is shifted to the first hermetically sealed space. Thus, the humidity within the first hermetically sealed space falls to accelerate the evaporation of the water reservoired within the first hermetically sealed space, thereby inducing a temperature drop.