To solve the problem that a space-heating/cooling device using a heat pump and a hot/cold air machine utilizing the endothermic and exothermic reaction of a thermo-module are large in size, complicated in constitution and heavy in weight.

This cold/heat-generating device is provided with a blower fan 5, a water holder 4 arranged in the blast passage of the fan, a water supply device 3 supplying the water to be held to the water holder, hydrated salt 2 held by the water holder and a heating means 8 heating the water holder. The heating means 8 heats the water holder in such a manner that the hydrated salt 2 becomes 2-hydraous salt or anhydrous salt at the time of generating heat, and heats the water holder in such a manner that the hydrated salt 2 changes into the state of 6-hydrous salt at the time of generating cold. Thereby, the cold/heat-generating device generates cold or heat.