The influence of soil organic matter on DNA adsorptions on soils was investigated by using an andosol sample including hydrogen peroxide (H202) treated and 673 K heated soils. The organic matter content of the andosol was decreased from 8.2 to 2.2% by the H202 treatment. The treatment raised DNA adsorption per unit weight on soil particles, although the surface area of the treated soil was 50% of that in the original soil. The 673K heated treatment removed the organic matter from the sample to 0.03% and decreased the surface area to 30% of the original soil. Nevertheless, the DNA adsorption of the heated soil was significantly higher than that of the original soil. These results suggested little contribution of soil organic matter to DNA adsorption on the andosol.