In order to conduct gene expression analysis of a number of genes in a number of cells, it has been necessary to separate cells, extract genes therefrom, amplify nucleic acids, and perform sequence analysis. However, separation of cells imposes damages on the cells, and it requires the use of an expensive system. Gene expression analysis in each cell can be carried out with high accuracy by arranging a pair of structures comprising a cell trapping section and a nucleic acid trapping section in a vertical direction to extract individual genes in relevant cells, synthesizing cDNA in the nucleic acid trapping section, amplifying nucleic acids, and analyzing the sequences using a next-generation sequencer.