A humidity controlling apparatus comprising: a moisture absorption unit including a base material rotatable about a rotation shaft and a macromolecular moisture absorbent provided in a layer on an outer periphery of the base material; and a heat source partially heating the moisture absorption unit, the macromolecular moisture absorbent having a hydrophilic state capable of absorbing moisture in the air and a hydrophobic state which releases the moisture sorbed in the hydrophilic state, the macromolecular moisture absorbent having a nature such that when temperature rises, the macromolecular moisture absorbent changes from the hydrophilic state to the hydrophobic state, and when the temperature falls, the macromolecular moisture absorbent returns from the hydrophobic state to the hydrophilic state, requires small thermal energy and can efficiently control humidity.