1. An automatic analyzer comprising: a dispensing section for dispensing a sample, including blood, and a reagent; a reaction section including a substrate having a plurality of reaction containers for allowing the sample including blood to react with the reagent therein; a photometry section for capturing an image of the inside of each of the reaction containers; an analysis section for analyzing the sample on the basis of whether or not reactions have occurred inside the reaction containers, wherein with a plurality of captured images obtained by capturing an image of the inside of the plurality of reaction containers corresponding to a plurality of categories of examination respectively, the analysis section calculates a photometric parameter of each of the images, and on the basis of the photometric parameter, and with a case where no reactions have occurred in the reaction containers being defined as negative, judges whether or not a measurement result based on the captured images is negative for each of the categories of examination, and analyzes characteristic information of the sample; a storage section for matching and storing the characteristic information of the sample and the measurement result; an extraction section for extracting the photometric parameter of the measurement result that is judged to be negative by the analysis section; and a determination processing section for calculating a difference between a maximum value and a minimum value of the photometric parameter extracted by the extraction section, determining whether or not the measurement result is valid using the calculated difference, and adding a result of the determination to the characteristic information of the corresponding sample.