PROBLEM TO BE SOLVED: To solve the problem that a conventional gelling agent for aqueous liquids is not suitable for air fresheners because it causes quality deterioration with the lapse of time, shows poor solubility to water of a raw material in the preparation of a water-based gel, produces a low transparency water-based gel, and causes deterioration of perfumes being raw materials due to the generation of ammonia in the preparation of the water-based gel.SOLUTION: A gelling agent for an aqueous liquid (D) contains: a reaction product (C) obtained by the reaction of a polymer (X) including, as an essential unit, at least one of monomer (A) selected from the group comprising a 5-10C ethylenic unsaturated polycarboxylic acid, its acid anhydride, fumaric acid and an ethylenic unsaturated monocarboxylic acid with an onium cation and/or ammonium and at least one crosslinking agent, selected from the group comprising following crosslinking agents: a polyvalent epoxy group-containing compound (B1), a polyvalent oxazoline group-containing compound (B2), a polyvalent carbodiimide group-containing compound (B3), and a polyvalent aziridine group-containing compound (B4).
