Provided is a method for measuring cholesterol in high-density lipoprotein (HDL) simply and accurately. A method for measuring cholesterol in high-density lipoprotein in a specimen, comprising reacting the specimen with i) a cholesterol ester hydrolase and a cholesterol oxidase, or ii) a cholesterol ester hydrolase, an oxidized coenzyme, and a cholesterol dehydrogenase, in an aqueous medium comprising at least one substance selected from the group consisting of pyridinium salts and quaternary ammonium salts each having a specific structure, and a polyanion to form hydrogen peroxide or reduced coenzyme and measuring the formed hydrogen peroxide or reduced coenzyme.