The utility model belongs to the technical field of the dehumidification, a dehumidifying device is provided. The utility model discloses in, judging as host system that humidity detection module detects the humidity value that obtains and is greater than firstly when predetermineeing humidity value, host system exports closing control signal to relay switch module to make power module supply power for the relay switch module, thus the actuation of relay switch module, and then power module supplies power for semiconductor refrigeration module, semiconductor refrigeration module condenses into water droplet with inside air at inside air current during through its cold junction, and water drain module discharges the water droplet to the box of outdoor case outside. Semiconductor refrigeration module dehumidifies to the inside air of outdoor case, is discharged outside the box of outdoor case because of the water droplet that condenses of dehumidification, thereby has consequently solved the problem that the current heating dehumidification outdoor incasement portion of easy messenger that the mode existed formation condensation brought the potential safety hazard.