A humidity sensor is provided. The humidity sensor includes a flexible substrate, a moisture absorption prevention layer covering the flexible substrate, a dielectric layer on the moisture absorption prevention layer, hydrophobic patterns on the dielectric layer, a first electrode between the moisture absorption prevention layer and the dielectric layer, and a second electrode spaced apart from the first electrode between the moisture absorption prevention layer and the dielectric layer. The first electrode has a thickness greater than that of the moisture absorption prevention layer.