A method of detecting PS2V characterized by comprising reacting PS2V in a sample with a primary antibody which is bonded to a solid phase and specifically recognizes PA2V, then reacting with a secondary antibody recognizing PS2 or PS2V by any of the following procedures: (a) reacting with a secondary antibody having been enzyme-labeled and recognizing PS2 or PS2V; (b) reacting with a secondary antibody having been biotinylated and recognizing PS2 or PS2V and then reacting with an avidinylated or streptoavidinylated enzyme; (c) reacting with a secondary antibody having been biotinylated and recognizing PS2 or PS2V and then reacting with a biotinylated enzyme and avidin or streptoavidin; and (d) reacting with a secondary antibody recognizing PS2 or PS2V and then reacting with an antibody having been enzyme-labeled and recognizing the secondary antibody; then adding the substrate of the above enzyme and detecting the product formed by the enzyme reaction.