The automatic analyzer stores: a predetermined period from the opening of a reagent vessel to the deterioration of the reagent; a reagent production lot number, reagent vessel unsealing time, and reagent expiration date as reagent information kept on a reagent-set-by-set basis; and relevant calibration curve factor information. The automatic analyzer judges whether a calibration curve factor for a reagent set is applicable or not to another reagent set of the analyzer with the same production number based on the predetermined period from the reagent vessel unsealing time and on the reagent expiration date.