A humidity sensor element includes a dielectric substrate, a nonporous conductive electrode disposed on the dielectric substrate, a permeable conductive electrode having a thickness in a range of from 4 to 10 nanometers and permeable by water vapor, and a detection layer sandwiched between the nonporous conductive electrode and the permeable conductive electrode. The permeable conductive electrode is parallel to the nonporous electrode. Both conductive electrodes have respective conductive leads attached thereto. The detection layer includes a copolymer having monomeric units comprising wherein M represents H, or an alkali metal. A humidity sensor including the humidity sensor element is also disclosed.