The present disclosure provides a humidifying device, including: a container, configured to accommodate a liquid; a first moisture absorptive member, partially or completely dipped in the liquid in the container; a second moisture absorptive member with air permeability, in contact with or isolated from the first moisture absorptive member; and a driving member, configured to control movement of the second moisture absorptive member, so as to allow the second moisture absorptive member to be in contact with or isolated from the first moisture absorptive member. The humidifying device according to the present disclosure can be applied in household appliances such as air cleaners and air conditioners. The operation and shut down of the humidification function is controlled, so as to avoid formation of superfluous air resistance when the humidification function is shut down. The present disclosure further provides an air cleaner and a household appliance, including the humidifying device provided according to the present disclosure. The air cleaner and the household appliance are not only simple in structure, effective in cost, and convenient in installation, but are also quiet when in operation.