To provide an epoxy resin composition which requires no advanced agitation skill or no strict control of the storage conditions for materials and has excellent circuit formability while securing the flowability of resin, even with use of inorganic filler having an average particle diameter of 1.5 μm or more and 5.0 μm or less, capable of producing a prepreg without occurrence of aggregation in varnish without requiring advanced dispersion technique.

The epoxy resin composition includes an epoxy resin, an epoxy resin hardening agent, a hardening accelerator, and an amorphous filler. The amorphous filler has an average particle diameter of 1.5 μm or more and 5.0 μm or less, a specific surface area of 4.0 m²/g or more and 7.9 m²/g or less, and a content ratio of filler having a particle diameter of 10 μm or less of 75 mass% or more. The mass ratio of SiO₂ component to the total addition amount of the amorphous filler is 25% or more.