The present invention provides an epoxy resin composition for a fiber reinforced composite material comprising an epoxy resin (A) comprising an epoxy resin (a1) having a weight average molecular weight of up to 1,000 and an epoxy resin (a2) having a weight average molecular weight of 10,000 to 100,000 which contains at least 20% by weight of the basic skeleton of the epoxy resin (a1), a thermoplastic resin (B), and a curing agent (C). The cured composition has a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and/or a continuous phase of the thermoplastic resin (B). A cured product having a high toughness can be obtained from this epoxy resin composition.