It is an object of the present invention to provide, for instance, a method for evaluating a function, such as transforming potential, of multiple different genes of interest, and a method capable of evaluating drug sensitivity of a subject having each gene of interest. The present invention relates to, for instance, a method for evaluating multiple different genes of interest, comprising the steps of: integrating, into host cell genomic DNA, polynucleotides each comprising a tag sequence and a gene of interest or a fragment thereof linked to the tag sequence; mixing a plurality of different host cells having the different polynucleotides integrated therein; culturing the mixed host cells; extracting the genomic DNA from the cultured host cells; quantifying each of the polynucleotides in the extracted genomic DNA based on the tag sequence; and determining a relative cell count of each of the host cells having the respective polynucleotides after the culturing, based on the quantified values for the polynucleotides.