PURPOSE: To obtain a water making device of good efficiency which utilizes the waste heat of waste gases effectively by so constituting the same that the waste gas of combustion utilized in the desorption process of the water making device using adsorbents is brought into direct contact with water of low grades.

CONSTITUTION: The outside air is passed alternately through the routes of an arrow A and an arrow B by a blower 3 to adsorb moisture alternately on adsorbing elements 1a, 2a. The adsorbed moisture is fed by a blower 10. It is desorbed by the high temp. gas heated with a heater 12, and is air-cooled in a condenser 18, whereby it is condensed and the condensate is stored in a water storage tank 19. On the other hand, the waste gas from the heater 12 is conducted to an evaporating tank 21, where it is brought into contact with the liquid drops of low grade water 22 sprayed from a nozzle 24 to allow the water to evaporate. This steam is conducted into a condenser 27 and is condensed to water which is stored in a water storage tank 31. The waste gas removed of the steam is released into the atmosphere through a duct 29.