The present invention relate to a method of detecting a genetic recombinant by using the PCR method. A method of quantitatively detecting method is provided whereby the total content ratio of the genetic recombinants and the individual content ratio of the genetic recombinant in a population containing plural genetic recombinant lines can be quantified. The method of the present invention comprises performing PCR for the DNA sequence specific to the recombinant and the endogenous DNA sequence shared by the species corresponding to the recombinant using, as a standard molecule, a molecule containing the DNA sequence specific to the recombinant and the endogenous DNA sequence shared by the species on the single molecule, and determining the content ratio of the number of molecules thereof.