A method of capturing exosomes comprising the steps of: injecting a first sample solution and a first buffer solution into a container, the first sample solution including exosomes expressing first detection target substances, second detection target substances, and third detection target substances, and the first buffer solution including first nanoparticles enclosing magnetic substances and fixing first binding substances which bind to the first detection target substances; mixing the first sample solution with the first buffer solution in the container so as to bind the first detection target substances and the first binding substances together to form first complexes of the exosomes and the first nanoparticles; isolating the first complexes from a mixed solution of the first sample solution and the first buffer solution, by bringing a magnet close to a side surface of the container to magnetically collect the first complexes on the side surface around the magnet; substituting the mixed solution by a second buffer solution to remove exosomes not expressing the first detection target substances; obtaining a second sample solution by moving the magnet away from the container so that the first complexes isolated by the magnetic collection are dispersed again in the second buffer solution; injecting the second sample solution including the first complexes in a well formed on a substrate on which second binding substances which bind to the second detection target substances are fixed; binding the second detection target substances of the first complexes and the second binding substances together, so as to capture the first complexes on the substrate; draining the second sample solution from the well and cleaning the well with a third buffer solution to remove exosomes not expressing the second detection target substances; and reacting a fourth buffer solution including second nanoparticles fixing third binding substances which bind to the third detection target substances with the first complexes captured on the substrate, and binding the third detection target substances and the third binding substances together, so as to bind the second nanoparticles to the exosomes of the first complexes which are captured on the substrate, thereby detecting only the exosomes expressing the first detection target substances, the second detection target substances, and the third detection target substances. injecting a first sample solution and a first buffer solution into a container, the first sample solution including exosomes expressing first detection target substances, second detection target substances, and third detection target substances, and the first buffer solution including first nanoparticles enclosing magnetic substances and fixing first binding substances which bind to the first detection target substances; mixing the first sample solution with the first buffer solution in the container so as to bind the first detection target substances and the first binding substances together to form first complexes of the exosomes and the first nanoparticles; isolating the first complexes from a mixed solution of the first sample solution and the first buffer solution, by bringing a magnet close to a side surface of the container to magnetically collect the first complexes on the side surface around the magnet; substituting the mixed solution by a second buffer solution to remove exosomes not expressing the first detection target substances; obtaining a second sample solution by moving the magnet away from the container so that the first complexes isolated by the magnetic collection are dispersed again in the second buffer solution; injecting the second sample solution including the first complexes in a well formed on a substrate on which second binding substances which bind to the second detection target substances are fixed; binding the second detection target substances of the first complexes and the second binding substances together, so as to capture the first complexes on the substrate; draining the second sample solution from the well and cleaning the well with a third buffer solution to remove exosomes not expressing the second detection target substances; and reacting a fourth buffer solution including second nanoparticles fixing third binding substances which bind to the third detection target substances with the first complexes captured on the substrate, and binding the third detection target substances and the third binding substances together, so as to bind the second nanoparticles to the exosomes of the first complexes which are captured on the substrate, thereby detecting only the exosomes expressing the first detection target substances, the second detection target substances, and the third detection target substances.