Abstract: An immunochromatographic device includes a sample application section; a determination section; and a capillary-flow section. The determination section has an immobilization section including one type of first antibody specifically reacting with all the types of target substances, or a plurality of types of first antibodies each specifically reacting with a corresponding type of target substance, the one type of first antibody or the plurality of types of first antibodies being immobilized. The sample application section or the capillary-flow section has a plurality of types of second antibodies each specifically reacting with all the types of target substances or a corresponding type of target substance. The plurality of types of second antibodies can be eluted. At least one type of second antibody specifically reacts with one type of target substance among the plurality of types of target substances. The plurality of types of second antibodies are labeled with different labeling substances.

Abstract: It is intended to present a sensor capable of labeling with more dyes, applying the labeled protein in immunochromatography making use of antigen-antibody reaction, and having an excellent sensitivity. In a buffer, a protein and a first covalent bonding compound that can react with this protein are reacted to prepare a protein conjugate, then a cyanine labeling dye is added in the buffer containing the protein conjugate, and the protein conjugate and cyanine labeling dye are reacted to prepare a dye labeled protein conjugate. Alternatively, in a buffer solution, a protein and a cyanine labeling dye are reacted to prepare a dye labeled protein, then a first covalent bonding compound that can react with the protein is added in the buffer containing the dye labeled protein, and the dye labeled protein and first covalent bonding protein are reacted to prepare a dye labeled protein conjugate.