DNA amplification and hybridization are successively carried out in a reaction system containing primers for the DNA amplification and hybridization probes, followed by detecting the hybrid in the reaction solution by affinity chromatography, wherein at least one of the primers to be used in the DNA amplification is labeled with a first labeling agent so that the amplified DNA will be labeled with the first labeling agent, a hybridization probe is labeled with a second labeling agent and contained in a reaction solution for effecting the DNA amplification, the base sequence of the hybridization probe is designed not to inhibit the DNA amplification, and a hybrid is detected by affinity chromatography with the use of the first and second labeling agents.