Provided is an epoxy resin composition for fiber-reinforced composite materials, which serves as a matrix resin for a prepreg. This epoxy resin composition is improved in tackiness stability during storage, while maintaining mechanical characteristics. The epoxy resin composition for fiber-reinforced composite materials is characterized by containing 25 to 50 parts by weight of an amine curing agent (B) selected from aliphatic polyamines, alicyclic polyamines and aromatic polyamines, and 1 to 20 parts by weight of an organic acid dihydrazide compound (C) having a melting point of not less than 150° C., per 100 parts by weight of an epoxy resin (A).