Dehumidifier characterized by using a simple and space-saving structure to prevent water from flowing out of a drainage tank when the drainage tank is taken out and delivered

An object of the present invention is to provide a dehumidifier capable of using a simple and space-saving structure to prevent water from flowing out of a drainage tank when the drainage tank is taken out and delivered. To achieve the object, the dehumidifier 1 is provided with: a humidifying device 3 for removing moisture from air; and a drainage tank 5 for storing the water discharged from the dehumidifying device 3. The drainage tank 5 includes: a water receiving portion (small cover 18) provided with a first opening 18a used as an entrance for allowing water to enter the drainage tank 5; and a non-return plate 19 which is disposed inside the drainage tank 5 at a position higher than the water surface (full water position 201) when the drainage tank 5 is filled with water, and faces the first opening 18a.