To execute inhalation treatment for several persons simultaneously by using plural atomizer by cleaning compressed air to be atomized by a filter device easy in the exchange and discharging the air from plural air discharging ports.

The cleaned high-pressure air passing through a compressor, an accumulated pressure tank and a filter unit 53 is introduced into each atomizer connected to plural air discharge ports, and is used for an inhalation treatment. The exchange time of each of filters 18, 19, 20 can be grasped with a sign display part changing the color in a clogging state from an observation window 77. Thus, the whole filter fixing plate 68 is taken off, exchanged to a new one, fixed to the body with screws and being built in a main body, thus the device can be continuously used.