The effect of water extracts of Fuscoporia obliqua, which is northern terrain Basidiomycetes, on anti-oxidation were studied in vitro. The analysis was done by using a spectrogram photometer to measure the elimination of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical. Consequently, high activity was shown in comparison with well-known functional Basidiomycetes such as Phellinus linteus or Agaricus blazei Murr. The anti-oxidization of Fuscoporia obliqua is not due to superoxide dismutase (SOD) as is widely believed, but a water-insoluble polymer element which became stable in the heat. These results indicate that the water-soluble lignin-like substance may be the main factor in the anti-oxidization activity from the color of the extract and analysis of the ingredients. The substance could be applied to various processed foods as a functional food which contain almost no protein or lipid.