An electrolytic cell capable of simply electrolyzing carbon dioxide into carbon monoxide and oxygen with low activation energy, and an electrolytic device. The carbon dioxide electrolytic cell includes a cathode, an anode, and a solid electrolyte having oxide ion conductivity. The cathode is the following (A) or (B); (A) a metal and a first mayenite-type compound are included therein or (B) a metal and a second mayenite-type compound are included therein, said second mayenite type compound including a mayenite type compound having electron conductivity.