An angiogenesis inhibitor effective in inhibiting angiogenesis which causes a disease is obtained by, for example, sterilely filtrating, disinfecting, and concentrating a product which is obtained as follows. That is, rice bran is extracted with hot water, the insoluble matter is filtrated, and the starch is decomposed by processing the filtrate with glucoamylase, thereby obtaining a water-soluble polysaccharide extract. Ammonium sulfate is added to a culture filtrate prepared by culturing Lentinula edodes of basidiomycetes, thereby obtaining an enzyme complex from the precipitate. This enzyme complex is added to the water-soluble polysaccharide extract, and the mixture is caused to react at a pH of 4.5 for 30 to 60 min and further react at a pH of 6.0 for 30 to 60 min, thereby biologically modifying the water-soluble polysaccharide extract and obtaining the product.
