Humidity controller apparatus

A humidity controller apparatus for removing moisture from or adding moisture to process subject air alternately using a first adsorption element (81) and a second adsorption element (82) by distributing first and second process subject air in a hollow casing (10) with first and second fans (95, 96) and switching distribution routes for the process subject air in the casing (10), wherein:

• the casing (10) has a flat rectangular shape and has first and second inlet openings (13, 15) and first and second outlet openings (14, 16);
• a suction-side wall (12), which is one of side walls of the casing (10), has the first and second inlet openings (13, 15) which are provided side by side in a longitudinal direction of the suction-side wall (12);
• the casing (10) has a filter room (44) extending along the suction-side wall (12), the filter room (44) being in communication with the first and second inlet openings (13, 15);
• and
• the filter room (44) contains an air filter (71, 76, 77) for filtering process subject air introduced through the inlet openings (13, 15).