Abstract: Disclosed are an immunochromatographic medium and an immunochromatographic method in which, even when plural items exceeding four items are detected which are the number of colors that can be detected by colored latex particles, the plural items can be detected and quantified simultaneously. The immunochromatographic medium comprises a support, a label-attached reagent immobilized on a labeling agent, and detection portions on which a material capable of combining with a substance to be detected in a sample is immobilized, the label-attached reagent and the detection portions being provided on the support, featured in that the labeling agent is a phosphor nanoparticle and the detection portions are shaped in the form of dots.