A novel method of specimen analysis in which prior to specimen analysis, any interfering substance can be measured. There is provided a method of specimen analysis, comprising the steps of irradiating a specimen with light to thereby obtain an optical information on the specimen from the specimen; mixing the specimen with a reagent to thereby obtain an analytical sample; and irradiating the analytical sample with light to thereby obtain an optical information on the sample from the analytical sample and processing the optical information on the sample to thereby accomplish analysis of the analytical sample. In the step of the analysis of the analytical sample, analytical conditions commensurate with the analytical sample are set on the basis of the optical information on the specimen.