METHOD FOR DETECTING AND MEASURING TARGET SUBSTANCE ON BASIS OF MEASUREMENT OF POLARIZATION ANISOTROPY, AND PARTICLES USED THEREFOR

To provide a method and kit for measurement of a target substance with high detection sensitivity, provided is a method of measuring at least any one of the presence or absence, and a concentration, of a target substance in a sample liquid, the method including the steps of: (a) preparing a first particle that specifically binds to the target substance and contains a rare earth complex, and a second particle that has a larger average particle diameter than that of the first particle and specifically binds to the target substance; (b) mixing the sample liquid, the first particle, and the second particle to provide a mixed liquid; and (c) determining at least any one of the presence or absence, and the concentration, of the target substance from polarization anisotropy of the mixed liquid obtained in the step (b).