A humidity control apparatus has a humidity control apparatus having a humidifying part for humidifying air and a dehumidifying part for dehumidifying to control humidity of a humidity control space. The dehumidifying part has: a main body part that is configured to encapsulate a working fluid therein and to cause a heat-pipe phenomenon. A heat-insulating part fits externally to the main body part and a heat absorption part absorbs heat from a base side part located on one side of the main body part in relation to the heat-insulating part and thereby condenses the working fluid that evaporated into gas in a front side part located on the other side of the main body part in relation to the heat-insulating part. The dehumidifying part dehumidifies the air by means of the front side part of the main body part where the working fluid in liquid form evaporates.