[Problem]To provide: a fiber-reinforced composite material having both Mode I interlaminar fracture toughness and compressive strength under wet heat conditions; an epoxy resin composition for producing the fiber-reinforced composite material; and a prepreg produced using the epoxy resin composition. [Solution] An epoxy resin composition comprising at least the following constituents [A], [B] and [C]: [A] an epoxy resin; [B] composite polyamide microparticles which satisfy such a requirement (b1) the materials constituting the particles are a polyamide (B1) and a thermoplastic elastomer resin (B2), such a requirement (b2) that the melting point or the glass transition temperature of the polyamide (B1) is higher than 100°C and such a requirement (b3) the number average particle diameter is 0.1 to 100 µ m; and [C] a curing agent.