Disclosed is an epoxy resin composition having low viscosity, high Tg and high elastic modulus, while having excellent fracture toughness. Also disclosed is a fiber-reinforced composite material which has achieved excellent thermal characteristics, compressive strength, impact resistance, fatigue resistance and perforated plate tensile strength by using the epoxy resin composition for fiber-reinforced composite materials. The fiber-reinforced composite material is most suitable as a material for producing aircraft. The epoxy resin composition contains at least the following components: [A] a predetermined bifunctional epoxy resin, [B] a liquid aromatic diamine curing agent and [C] core-shell polymer particles. The epoxy resin composition is characterized in that the component [C] containsan epoxy group in the shell portion, while having a volume average particle diameter within the range of 50-300 nm.