A water level detecting device and a dehumidifier including the same are provided. The water level detecting device comprises a guide arranged within a water container for collecting a condensate water generated as a dehumidifying function is performed, a sensing object inserted within the guide and configured to ascend on the condensate water collected in the water container, and a sensor arranged in a main body of a dehumidifier which the water container is mounted to and dismounted from, and configured to sense a movement of the sensing object. The water level of the water container is set to any of at least two different water levels according to an inserting direction of the sensing object inserted into the guide.