The present invention provides Hsp90 family protein inhibitors comprising, as an active ingredient, a benzoyl compound represented by general formula (I): (wherein n represents an integer of 0 to 10； R 1 represents substituted or unsubstituted lower alkoxy, substituted or unsubstituted lower alkoxycarbonyl, CONR 7 R 8 or the like； R 2 represents substituted or unsubstituted aryl, a substituted or unsubstituted aromatic heterocyclic group or the like； R 3 and R 5 , which may be the same or different, each represent a hydrogen atom, substituted or unsubstituted lower alkyl, substituted or unsubstituted lower alkenyl or the like； and R 4 and R 6 , which may be the same or different, each represent a hydrogen atom, halogen, substituted or unsubstituted lower alkyl, substituted or unsubstituted aryl or the like) or a prodrug thereof, or a pharmaceutically acceptable salt of said benzoyl compound or said prodrug.
