Patent ID: 7368252

Claim:
An immunoassay method of a prostate-specific antigen comprising: performing an antigen-antibody reaction comprising, contacting a sample with an antibody to a prostate-specific antigen in the presence of a copolymer as an agglutination accelerator, which is dissolved in a reagent, and is obtained by polymerizing a monomer represented by the following general formula [2]: wherein, R 1 -R 3 are each independently a hydrogen atom or an alkyl group optionally having a hydroxyl group; R 4 is an alkylene group; R 5 is an alkylene group optionally having a substituent and optionally having an oxygen atom in the chain; R 6 is a hydrogen atom or a methyl group; and X is an oxygen atom or a —NH— group, and an aralkyl methacrylate; measuring a degree of agglutination derived from the antigen-antibody reaction; and determining an amount of prostate-specific antigen in the sample based on the degree of agglutination derived from the antigen-antibody reaction.