<p>Using an antibody-carrying membrane having carried a first antibody on a porous carrier membrane and an antibody-carrying latex having carried a second antibody having an antigenic determinant different from the first antibody on latex colored with a color different from that of the carrier membrane, an analyte can be assayed in a simple manner with high sensitivity. This assay method utilizing immunological reaction is characterized by visual determination and judgment of the results by change or contrast in color.</p>
