An object of the present invention is to discover an endogenous wheat sequence satisfying the conditions of: a) it is universally present in varieties of wheat, b) the amount present (detected amount) is not affected by the wheat variety, c) even if other grains are present, only wheat can be detected without cross-reactivity, and d) it is amplified quantitatively by the PCR reaction. A further object of the present invention is to provide a method of accurately detecting and quantitating endogenous wheat DNA in a test sample by the polymerase chain reaction. The present invention provides a method of detecting or quantitating endogenous wheat DNA in a test sample by the polymerase chain reaction, the method comprising: a step of using a nucleic acid molecule in the test sample or a nucleic acid molecule extracted from the test sample as a template to amplify the nucleic acid molecule of a region consisting of the nucleotide sequence identified as SEQ ID NO: 2 or a partial sequence thereof with a primer pair capable of amplifying that region; and a step of detecting or quantitating the amplified nucleic acid molecule.