To provide a humidity controller, capable of being cleaned easily by removing a insect-repellent filter.

A insect-repellent filter 28 is mounted, such that a rib 28a formed into a U-shape in cross section and a partition plate 18a for partitioning the upper and lower parts of a supply and exhaust duct 18 from each other are fitted in each other from the end part on the indoor side of the supply, and the exhaust duct 18 with which a supply and exhaust cylinder 29 situated fronting on an outdoor space from the indoor side and extending from the internal part of the body of a humidity controller 1 communicates and connects in retractable manner.