A characteristic value of a plurality of biological samples is optically acquired from a specimen, the characteristic value is compared with prior inspection information for the same specimen, and onthe basis of the comparative results, an index is calculated for determining whether to carry out a continuation of processing to genetic analysis of the biological sample or to readjust the sample from the same specimen. Thus, in analysis of a single cell or analysis of a small numbered group of cells, the cost of analysis, time for analysis, and effort can be restrained while suitably selectinginspection samples and securing validity, thereby detecting biomarkers with greater reliability.