Detection of amplicon contamination during pcr exhibiting two different annealing temperatures

The method for performing the PCR reaction using one set of a primer containing the arrangement element which plays a role of tugging arrangement in a target sequence including a complementary arrangement element. By carrying out the amplification reaction at a different temperature, existence of mixing (contamination) produced from the amplification product of a former reaction can be determined, and the reliability of a reaction can be improved, and the necessity for a contrast reaction and reaction reappearance can be reduced.