PURPOSE: To enhance water making efficiency in production of water from atmosphere by a method wherein the weight of adsorbent layer is detected by a load cell to obtain the water adsorption condition in the adsorbent layer and the result is used to make an optimum switching of adsorption-desorption processes.

CONSTITUTION: When the water content adsorbed by adsorbent layer 1 increases, the weight of the layer 1a is detected by a load cell 103. Judgment device 106 finds that the electric output from amplifier 105 is at a desired value between before adsorption process and after its completion and causes realy 107 to stop operation so that the first indication circuit is made to open circuit. When adsobed water is increased to reach a water content sufficient for desorption process, the judgement device 106 checks that the output from the amplifier 106 is at the desired value to indicate completion of adsorption. The device 106 actuates relay 110 and closes the second indicator circuit so that the lamp 111 lights to indicate the completion of adsorption process.