In the course of screening for the antimicrobial compounds contained in rare mushrooms, we isolated bisnoryangonin from Pholiota aurivella . The structure of bisnoryangonin was identified by HRESI-MS and NMR spectral data (1-D ( ¹H- and ¹³C-NMR) and 2-D (HMQC and HMBC)). This is the first report on the presence of bisnoryangonin in Pholiota aurivella . The antimicrobial activities of bisnoryangonin against two microbial organisms ( Bacillus megaterium and Microbacterium foliorum , which were isolated as food contaminants) were tested. Bisnoryangonin showed more potent antimicrobial activity than butyl-4-hydroxybenzoate which is used as a food additive.