Discharge electrodes for generating ion and a member for cleaning the discharge electrodes are mounted on an electrode support frame, which is detachably attached to the case of an ionizer. When the electrode support frame is attached to the case, the cleaning member occupies a retraction position where the cleaning member does not shut off or disturb air that is supplied from a fan. Upon the detachment of the electrode support frame from the case, the cleaning member becomes moveable. Then, the cleaning member is moved while being brought into contact with the discharging parts of the discharge electrodes one after another. As a result, the cleaning member sweeps dust or other particles off the discharging parts thereof.