A
humidity sensor element which has an electrical insulator substrate, a pair of electrodes being disposed thereon opposite to each other via a gap, and a
humidity-sensitive thin film formed on the gap, wherein the
humidity-sensitive thin film comprises a
polymer or a
copolymer derived from a
monomer having the formula (1): (1) wherein A11 is a
divalent group, R11 to R14 are each an
alkyl group, Y11 and Y12 are each a monovalent group having an ethylenically unsaturated reactive group at the terminal thereof, arbitrary two or more of R11 to R14, Y11, Y12, A11 and a part of the
nitrogen atom (N) side of them may form a ring together with a
nitrogen atom (N), and X11<-> and X12<-> are each an anion, and the substrate is optionally subjected to a treatment by a physical means or the like; and a method for manufacturing the humidity sensor element. The humidity sensor element is used for detecting and determining the
moisture in an
atmosphere, and is excellent in the resistance to water, a
solvent and a gas, is free from
hysteresis over a wide range of humidity, and has stable output characteristics.