In order to decode arbitrary sequence regions for a large number of genes in a large number of cells, it is necessary to fragment the nucleic acids and introduced a sequence, which differs for each the cell, in the respective fragments. However, in conventional constructions for analyzing large numbers of cells, there was the problem that the cleaved fragments of different regions were intermingled before a tag sequence unique to each region could be introduced. The present invention is constructed to also comprise a genetic analysis system, when trapping nucleic acids extracted from a cell in multiple regions on a substrate and synthesizing and fragmenting the complementary DNA strands (cDNA) of the nucleic acids for each individual region, for immediately introducing a tag sequence unique to each of the regions into said fragments.