PURPOSE: To permit the speedy inspection by reducing the number of times of reinspection, eliminate the uselssness of samples and reagents, and prevent the deterioration of the actual processing faculty of an automatic analyzing device.

CONSTITUTION: The limit absorbancy within the absorbancy range for obtaining the concentration of the inspected component of a sample with high reproducibility from the absorbancy variation (rate) is determined, and the absorbancy variation rate of the inspected liquid in a reaction process is measured at plural times by using a a plurality of standard samples having different concentration, and the concentration conversion coefficient for converting absorbancy variation (rate) to concentration at each time of a plurality of reaction times which are previously determined for the absorbancy of each standard sample which satisfies the limit absorbancy. The absorbancy variation (rate) of an unknown sample is measured at plural times in a reaction process, and the absorbancy at each reaction time ranging from the longer reaction time to the shorter reaction time among the previously determined plural times is compared with the limit absorbancy, and the reaction time satisfying the limit absorbancy and the absorbancy variation (rate) at that time are adopted, and the concentration of the inspected component is obtained by using the concentration conversion coefficient and the reagent blank value at the adopted reaction time.