Disclosed is an air purifier able to maintain the normal state of drive of a disk-shaped humidification filter by controlling the state of rotation of the humidification filter. The air purifier can maintain the normal state of drive of the humidification filter by using a stepping motor and the control unit in order to vary the state of rotation of the humidification filter and thereby remove extraneous material when the humidification filter is rotating abnormally due to extraneous material.