The present invention achieves accurate quantitative determination without reducing measurement throughput and also without having to add a multi-component reference standard. An analytical instrument of the present invention for determining the concentration of a target compound contained in a target sample includes: a means for ionizing a mixture having a specific compound added to the target sample; a means for performing mass analysis on resulting ions; and a database that stores dependence of signal intensity on the concentration of a specific matrix component for each of the target compound and the addition compound, wherein the database is used to calibrate the concentration of the target compound from a signal derived from the target compound and a signal derived from the addition compound, each signal obtained by the mass analysis means. The present invention achieves a multi-component analyzer using low-cost, high-throughput mass analysis, as compared to conventional technique.