An object of the present invention is to provide an epoxy resin composition capable of providing a carbon fiber-reinforced composite material that is excellent in moldability, heat resistance, and mechanical properties such as tensile strength and compression strength, and a prepreg. The present invention provides an epoxy resin composition containing at least components [A] to [D] shown below: [A]: an epoxy resin having a xylene group; [B]: a glycidyl amine epoxy resin having three or more glycidyl groups in a molecule; [C]: a thermoplastic resin; and [D]: an aromatic polyamine, the epoxy resin composition containing 10 to 80 parts by mass of the component [A] and 20 to 90 parts by mass of the component [B] based on 100 parts by mass in total of epoxy resins, and also 1 to 25 parts by mass of the component [C] based on 100 parts by mass in total of epoxy resins.