Disclosed is a sustainedly drug-releasing hydrogel contact lens which can sustainedly release an anionic medicament such as an allergy-treating agent in a mildly irritating and effective manner while achieving vision correction. Specifically disclosed is a hydrogel comprising ionic monomers composed of at least a cationic monomer and an anionic monomer, wherein the component ratio of the ionic monomers is 5 to 20 mol % inclusive relative to the total amount of monomers that constitute the gel, and the content of the anionic monomer is 15 to 25 mol % inclusive relative to the content of the cationic monomer.
