In a carbon dioxide reduction method according to the present disclose, used is a carbon dioxide reduction device comprising a cathode container in which a first electrolyte containing carbon dioxide is stored, an anode container in which a second electrolyte is stored, a solid electrolyte membrane, a condenser, a cathode electrode having a metal or a metal compound on the surface thereof, and anode electrode having a region formed of a nitride semiconductor layer in which a GaN layer and an AlxGa1-xN layer are stacked. The anode electrode is irradiated with light condensed by the condenser and having a wavelength of not more than 360 nanometers to reduce the carbon dioxide contained in the first electrolyte on the cathode electrode.