A humidifier is disclosed. The present humidifier comprises: a humidifying member; a storage water container that is located above the humidifying member and accommodates water; a circulation water container that is located below the humidifying member and accommodates a certain amount of water; a circulation pump that supplies water from the circulation water container to the humidifying member; a valve that selectively supplies water from the storage water container to the circulation water container; and a drainage member that selectively discharges water from the circulation water container.