A flame retardant epoxy resin composition containing(A) a phenolic novolak type epoxy resin including a phenolic novolak type epoxy resin of the following formula (1) and/or formula (2) in a total of at least 50 wt %: ##STR00001## (wherein, n is 0 or a positive integer) ##STR00002## (wherein, n is 0 or a positive integer) (B) a bisphenol type epoxy resin not containing a halogen, (C) an inorganic filler, and (D) an organic flame retardant. A prepreg and a fiber-reinforced composite using this epoxy resin composition.