To resolve problems of a filter cartridge constituting a chemical filter unit wherein three kinds of the filter cartridges are needed for organic gas, acidic gas and alkaline gas, respectively, requiring a large installation space for the chemical filter unit composed of the filter cartridges, preventing installation of the chemical filter unit in a conventional air conditioning system, requiring large scale of modification for additional installation, and causing increase of cost.

The filter cartridge constituting the chemical filter unit is constituted of a casing formed of a detachable lid plate and side plates for other ends, punching plates attached to whole openings of front and rear faces of the casing, and punching partition plates attached to hollow parts of the casing. Particulate adsorbing materials of different types of ion exchange groups are packed in two or more of packing chambers formed by the punching partition plates attached to the hollow parts of the casing.