An object of the present invention is to provide a kit in which a quantitative determination of a substance to be measured in a biological sample can be carried out with high accuracy, even in a case where the substance to be measured includes a plurality of substances having different structures. According to the present invention, a kit for quantitatively determining a substance to be measured in a biological sample, the kit including fluorescent particles that have a first binding substance capable of binding to the substance to be measured; and a substrate that has a detection region having a second binding substance capable of binding to any one of the substance to be measured and the first binding substance, in which the substance to be measured includes at least three types of substances having different structures, and the first binding substance includes at least three types of binding substances which are capable of binding to the at least three types of substances having different structures, respectively, is provided.