Provided is a method for producing a good epoxy resin composition for obtaining fiber-reinforced plastics. A production method for obtaining a fiber-reinforced composite material by impregnating a fiber assembly with an epoxy resin composition and then curing the epoxy resin composition, wherein the epoxy resin composition contains a component [A], a component [B] and a component [C] respectively satisfying the conditions described below. When the blending amount of the component [B] is set to b parts by mass and the blending amount of the component [C] is set to c parts by mass relative to 100 parts by mass of the component [A] contained in the epoxy resin composition, formula (2) is satisfied within the range of formula (1), formula (4) is satisfied within the range of formula (3), and formula (6) is satisfied within the range of formula (5). The epoxy resin composition is blended at a temperature of 60-80°C (inclusive).