Provided is a method of detecting or quantifying a wheat species-specific DNA in a test sample by polymerase chain reaction. The method comprises a step of amplifying a nucleic acid molecule having at partial sequence of a nucleotide sequence identified as SEQ ID NO: 1 using a nucleic acid molecule in the test sample or a nucleic acid molecule extracted from the test sample as the template and using a primer pair capable of amplifying the partial sequence and a step of detecting or quantifying the amplified nucleic acid molecule.