An analytic method uses a labeled antigen, labeled antibody, tracer, etc. in which a radio isotope, fluorescent dye, luminescent dye, enzyme, etc. is bonded to an antibody or an antigen bonded to a protein as an object of analysis for performing an assay of a trace amount of a substance such as a hormone, tumor marker, infective pathogen marker, infective antibody, etc., for blood, serum, plasma, or body fluid as a sample or specimen. The analysis is enabled at high sensitivity, with less generation of noises and at low background. When an assay is performed based on the antigen-antibody reaction for a sample in an analytic method by fluorometry or luminometry, detection or measurement of non-specific fluorescence or luminescence such as interference light is eliminated or removed effectively irrespective of the property of the sample or the level of the concentration of substances contained in the sample.