A method of inhibiting angiogenesis by applying a protein polysaccharide of a (1→6)-β-D-glucan with a glucan:protein ratio of 55:43 [w/w], obtained by extracting with a 5 w % aqueous solution of sodium hydroxide a residue of extraction and removal of water-soluble polysaccharides from the Agaricus blazei Murill (himematsutake) fruiting body, and a food/beverage composition for angiogenesis inhibition containing the protein polysaccharide of (1→6)-β-D-glucan.