Epoxy resin composition, prepreg, and fiber-reinforced composite material

An epoxy resin composition comprising components [A], [B], [C] and [D] and satisfying requirements (1), (2), and (3) and (4):

• [A]:
• at least one epoxy resin selected from the group consisting of a bisnaphthalene epoxy resin, a dicyclopentadiene epoxy resin, a biphenyl aralkyl epoxy resin, and a naphthalene aralkyl epoxy resin,
• [B]:
• a core-shell type particulate rubber,
• [C]:
• dicyandiamide, and
• [D]:
• a borate ester,
• wherein:
• (1) the component [B] accounts for 6 to 18 parts by mass relative to the total quantity of epoxy resins, which accounts for 100 parts by mass,
• (2) a cured epoxy resin produced by curing the epoxy resin composition at 135° C. for 2 hours shows a rubbery state elastic modulus G′ in a range of 8 MPa<G′<15 MPa as determined by dynamic viscoelasticity analysis,
• (3) the cured epoxy resin shows a tensile fracture strain of 7% or more, and
• (4) the component [D] satisfies:
• 0.003≤(number of parts by mass of component [D]/number of parts by mass of component [B])≤0.05.